~A Book of Experiments~ For use in teaching elementary School science Organized to support the Massachusetts Science and Technology/Engineering Curriculum Frameworks Compiled by Grade 11 Scientific and Technical Writing Students at the Massachusetts Academy of Math and Science at WPI Fall 2009 Table of Contents Massachusetts Science and Technology/Engineering Curriculum Framework: Physical Sciences Learning Standards--Grades 3-5 Differentiation between properties of objects (e.g. size, shape, and weight) and properties of materials (e.g. color, texture, hardness): Density Cauldron Bubbles Making a Lava Lamp Making a Flinker Polishing Pennies Floating Eggs Compare and contrast solids, liquids, and gases based on the basic properties of these states of matter: Balloon Bottle Blow-Up Can you blow up a balloon with a lemon? The Rising Hand The Great Pepper Dispersion Cloud Dough Splitting Water Pouring Water Sideways Surface Tension Lifting an Ice Cube That Which Doth Not Mix Sink a Dime Air Takes Up Space Gravity Free Water Under Pressure? Capillary Action Air Currents: Heat Rises Air Pressure Candles and Air Pressure Humpty Dumpty Had a Great Fall Oobleck Cornstarch, Water, and Oobleck Carbon Dioxide Fire Extinguisher Shrinking Water Bottle Identify the basic forms of energy (light, sound, heat, electrical, and magnetic). Recognize that energy is the ability to cause motion or create change: Friction Sliding vs. Rolling Friction Give examples of how energy can be transferred from one form to another: Burning Money Rubber Band Car Identify and classify objects and materials that conduct electricity and objects and materials that are insulators of electricity: Laws of “Attraction” Electrified Dice Bending Water Fun with Static Electricity Charge for Cheerios Recognize that magnets have poles that repel and attract each other: Magical Magnetism Make an Electromagnet Floating Paper Clip Recognize that light travels in a straight line until it strikes an object or travels from one medium to another, and that light can be reflected, refracted, and absorbed: Sky in a Jar Making a Rainbow Somewhere over the Rainbow Miscellaneous Science and Math Activities: The Water Drop Microscope Pendulums Density Materials 1/8 cup water 1/8 cup vegetable oil 1/8 cup corn syrup 1 clear plastic cup Procedure Pour 1/8 cup of corn syrup into the clear plastic cup. Pour 1/8 cup of water into the same cup. Pour 1/8 cup of vegetable oil into the cup. What do you see? Record observations. Stir the mixture until it appears to be completely mixed. What happens? Record observations. The Scientific Explanation The vegetable oil, water and corn syrup do not mix because the liquids have different densities. Liquids with different densities do not combine because one liquid is heavier than another; in this case all three liquids have different densities. When these liquids are stirred or shaken they separate over a period of time, with corn syrup on the bottom, water above the corn syrup, and vegetable oil on the top. The bottom liquid is the heaviest, and the liquid directly above it is the second heaviest and so on. This means corn syrup is the heaviest liquid, water is the second heaviest liquid, and vegetable oil is the third heaviest liquid. Cauldron Bubbles Materials: ¾ cup water ¼ cup olive oil or vegetable oil Salt (NaCl) 1 tall, clear glass or plastic bowl Teaspoon Procedure Fill the glass halfway with water. Add about an inch of oil in the glass. Let all of the oil settle out on top of the water. Add some salt in the glass using a teaspoon. Notice what happens to the salt and the oil. Wait until some of the salt on the bottom dissolves and see what happens. See if you can make cauldron bubbles with other substances like sugar or sand. The Scientific Explanation Density is how tightly packed matter is in an object. Different substances have different densities. When water and oil are put in the same glass, the oil seems to float on top of the water. This is because oil is less dense that water, so it settles out on top. When a substance is denser than oil and water, it will settle out on the bottom of the glass. When you add the salt in the glass, a bubble of oil is formed around it. Because the salt and the oil put together are denser than the water, the bubble sinks to the bottom. But, when the salt dissolves, the bubble of oil floats back up to the top because it is less dense than the oil again. Lava Lamp Materials 1/3 cup vegetable oil 1 Table spoon salt 1 cup water Tall drinking glass Procedure Take a tall drinking glass and fill it about 2/3 with water. Pour vegetable oil into the cup until the oil is 1 cm thick. Fill a table spoon with salt. Sprinkle the salt into the cup. What do you see? Scientific explanation Density is the measurement of mass and volume. When a water (higher density) is mixed with oil (lower density), the oil floats on top. Salt has a density that is higher than either oil or water, so when salt is added, sinks to the bottom of the glass, carrying some oil with it. As the salt begins to dissolve in the water, the oil is released and floats back up to the top of the glass. The oil and water didn‟t mix because they have different polarities. Water has a charge (like a magnet) that attracts other substances. Oil on the other hand does not have a charge. That is why when going through water oil looks like little bubbles but doesn‟t mix with the water. Making a Flinker Materials styrofoam peanuts paperclips of various sizes a container of water Procedure Work in pairs Obtain a few Styrofoam peanuts and paper clips Fill a container with water Now drop one paper clip and one Styrofoam peanut into the container Which object floats and which object sinks? Floats: ________________________ Sinks: ________________________ Using your Styrofoam peanuts and paperclips brainstorm and try to create an object that flinks! Flinker: A flinker is an object that does not float or sink; it is suspended midway in the body of water. (Hint*) you can combine the paper clips with a foam peanut by unraveling the paper clips and puncturing the peanut. (Hint*) you may need to squeeze your Styrofoam peanut occasionally because when it gets extremely soaked through it works much worse. The Scientific Explanation Through this experiment the scientific principle of density is illustrated. The density of water is equal to one, and if an object has a greater density then water it will sink, and if density is less than that of water it will float. A flinker will have a density of one because it is suspended midway in the body of water. This experiment begins to introduce children to the principle of density. As children get older, during eighth or ninth grade they will go deeper into the principle of density and learn that density = mass / volume. Polishing Pennies Materials: Dishwashing detergent Distilled white vinegar Lemon juice Cola Distilled water 5 rusted copper pennies 5 small plastic cups or containers 1 disposable plastic spoon A measuring spoon that measures teaspoons A measuring cup (measures cups) A large glass Procedure Pour 1 cup of water into the measuring cup and pour it into the tall glass. Measure ¼ teaspoon of detergent with the measuring spoon and pour the liquid into the tall glass, too. Stir the water and detergent in the glass with the plastic spoon. Place a penny in each of five small plastic cups. Pour enough lemon juice, vinegar, detergent solution, water, and cola to completely submerge a penny into separate cups. Each cup should have a penny and a different liquid in it. Let the pennies sit in the liquids for five minutes. What changes in the cups do you notice? After the five minutes, remove each penny from the cups with the plastic spoon, placing each coin on the work surface. Clean the spoon after each removal. Dry the pennies with a paper towel and note any removable substances. Pour the vinegar, lemon juice, water, cola, and detergent down a sink drain. Scientific Explanation The pennies are made from copper, which reacts with the air to form a thin oxide coating. This is because copper atoms are positive, and the oxygen atoms in the air possess negative properties. Like magnets, the positive and negative charges attract each other to form new compounds. The acids in the cola, lemon juice, and vinegar remove the oxides, but the detergent and water do not react with the penny surfaces. This explains the occurrence of the substance that was removed from the penny in the vinegar with the paper towel. Floating Eggs Materials 1 raw egg 1 beaker 1 teaspoon Bag of salt Balance (triple beam or electronic) Procedure Take the mass of the beaker. Fill the beaker about halfway and record the amount of water inside (the volume). Take the mass of the beaker with the water in it. Calculate the mass of the water by subtracting the mass of the beaker from the mass of the beaker with water. Take the mass of the egg. Tilt the beaker and gently slide the egg in. Don‟t let the water splash out! Record how much water the egg displaced. This is the volume of the egg. Add one teaspoon of salt at a time to the water. Record results after adding every spoon of salt. How many teaspoons of salt does it take before the egg starts floating? Take the egg out of the water using the spoon. (Try not to remove any water) Take the mass of the beaker and salt water. Calculate the mass of the salt water by subtracting the mass of the beaker from the mass of the beaker with salt water. Calculate the density of the water, egg, and salt water. Density is calculated with the formula mass/volume. Compare the densities. The Scientific Explanation The egg floats on salt water but not on cold water because of density. Density is the measure of the compactness of a substance ― how closely the atoms of the substance are packed together. Density is calculated with the formula mass/volume. This experiment also demonstrates the concept of buoyancy. Buoyancy is the concept that something with a smaller density will float on a liquid with a higher density. This experiment demonstrates that salt water is denser than fresh water because the egg will float in the salt water but not in the fresh water. This experiment also shows that items with a smaller density float on items with a higher density. Balloon Bottle Blow-up Materials 1 Balloon About 40 mL of water 1 20 oz. soda bottle Drinking straw Vinegar About 1 teaspoon of baking soda Procedure Stretch out the balloon before beginning so that it will be easier to blow up the balloon. Pour the water and the baking soda into the soda bottle and stir the mixture with the drinking straw. Pour in the vinegar, and quickly stretch the balloon over the mouth of the bottle. Start shaking the bottle right after the balloon is stretched over the bottle. Make sure to time how long it takes for the balloon to blow up. Repeat the entire process again, but do not shake the bottle and time how long it takes for the balloon to blow up now. The Scientific Explanation The balloon will inflate. Adding vinegar to the baking soda and water creates a chemical reaction. The baking soda is a base, and the vinegar is and acid. When the acid and base come into contact, they make carbon dioxide. It rises up through the bottle and into the balloon, filling it with the carbon dioxide. It fills up faster when you shake the bottle because the vinegar and baking soda are mixed together more to make more carbon dioxide. You can also use lemon juice instead of vinegar as an acid. Can You Blow Up A Balloon With A Lemon? Materials 1 lemon cut into two halves A measuring cup A balloon An empty soda or water bottle 1 oz. of water (30 mL) A teaspoon (5 mL) Baking soda Procedure Cut the lemon in half and squeeze as much lemon juice possible from both halves into the beaker or small container. Hold a balloon at both ends and stretch it back and forth a few times. Carefully pour 1 oz. (30 mL) of water into the empty soda or water bottle. Make sure it is clean. Dissolve 1 teaspoon of baking soda (5 mL) in the bottle. Pour in the lemon juice as well and swirl the contents of the bottle around a few times so that the solutions mix. Fit the opening of the stretched balloon over the mouth of the bottle. What happens? The Scientific Explanation Baking soda is sodium bicarbonate, a base, and lemon juice is an acid, which tastes sour. When carbonates and acids are mixed together, carbon dioxide is produced. This gas is what floats up into the balloon and makes it expand. This experiment can be extended by changing the experiment slightly. More baking soda or more lemon juice can be used to see which produces more carbon dioxide (which causes the balloon to be bigger). This experiment can also be tried without using any water and seeing if there are any effects on the reaction. The Rising Hand Materials Three teaspoons of white vinegar One medical latex glove Two teaspoons of baking soda A glass jar with a wide mouth Procedure Fill the jar with three tablespoons of white vinegar. Take out one glove from the box and pour two tea spoons of baking soda inside. Wrap the base of the glove over the mouth of the jar, making sure that no baking soda falls in just yet. When you are ready, take the attached glove and put it inside the jar. What happens? The Scientific Explanation When vinegar and baking soda are mixed in a container, they react violently. The acetic acid in vinegar and the sodium bicarbonate in baking soda combine and form carbonic acid. However, carbonic acid is very unstable and can't hold itself together. Thus the acid falls apart into two compounds: carbon dioxide (the gas you breathe out) and water. The carbon dioxide produced is heavier than the air inside the jar so it pushes the air out of the way. Since air is a gas and is being forced out by carbon dioxide, it advances upward. The air then pushes up on the glove and viola, the glove rises! After all gasses break free, the resulting liquid in the jar is a mixture between water and leftover sodium acetate. The overall reaction is as follows: NaHCO3 (aq) + CH3COOH (aq) → CO2 (g) + H2O (l) + CH3COONa (aq) The Great Pepper Dispersion Materials: 1 shallow bowl About 3 cups of room temperature water Pepper 1 teaspoon of hand soap Procedure: Pour the water into the shallow bowl so that there is a liquid layer at least 1 inch deep. Sprinkle pepper over the surface of the water so that is covers the surface evenly. Pour the hand soap into the center of the bowl. Observe the movement of the pepper to the outer rim of the bowl. The Scientific Explanation: Water has an adhesive quality similar to glue that causes it to stick to other water molecules and the pepper. The sticky water molecules on the surface of the bowl form a film on the liquid surface called water tension. Soap breaks this tension. The water sticks to the soap rather than the pepper. The water molecules on the edge of the bowl that have not touched the soap are still pulling on the pepper. Without an even amount of molecules pulling on the pepper in each direction, it travels to the side of the bowl that is pulling the strongest. That is why all the pepper moves away from the soap. The soap isn‟t pushing the pepper away. The water molecules on the outer rim of the bowl are pulling on the pepper harder than the water molecules in the middle. Cloud Dough Materials 2 cups flour 1 tablespoon powdered Tempera 1/3 cup vegetable oil 2/3 cup water A medium size mixing bowl A measuring cup A tablespoon Optional: Food Coloring Procedure Pour the flour and vegetable oil into the bowl Mix the flour with the oil (and color if desired) Add directed amount of powdered tempera and mix well Slowly add water and simultaneously knead the mixture well If necessary, add more water in small amounts Continue kneading the mixture until the dough is soft and elastic Store dough in a refrigerator (in a covered container) if it needs to be preserved The Scientific Explanation This experiment is used to demonstrate basic chemistry principals. It displays how molecules in different compounds mix together, and how they can form a new compound with an entirely different consistency. When the vegetable oil is added to the flour it gives the resulting mixture a more solid consistency. The powered tempera is added as a reactant to maintain that consistency while the water is being added. Powdered tempera is made from a mixture of corn starch, dried and powdered egg yolks, and other chemicals that are used to absorb liquid. So instead of turning this mixture into a liquid-like mess, it creates an even more solid form for the mixture. The end result of this experiment is the creation of a soft, elastic dough, which is similar in the consistency to that of PlayDough. Splitting Water Materials A 9 volt battery Two regular number 2 pencils (remove eraser and metal part on the ends) Salt (1 teaspoon) Thin cardboard Electrical wire Small glass (about 1 cup size) Water (about ¾ cup) Tape Procedure Remove eraser and metal parts from the ends of each pencil. Sharpen each pencil at both ends. Cut the cardboard to fit over glass. Push the two pencils into the cardboard, about an inch apart. Dissolve about a teaspoon of salt into the warm water by stirring and let sit for 3 minutes. Using one piece of the electrical wire, connect one end on the positive side of the battery and the other to the black graphite (the "lead" of the pencil) at the top of the sharpened pencil by wrapping it around. Do the same for the negative side connecting it to the second pencil top. It is helpful to use tape to help secure the wire to the batteries, just be sure that the wire is still touching the battery parts. Place the other two ends of the pencil into the salted water. What do you observe happening at the tips of the pencils? The Scientific Explanation The electricity from the battery is passed through the wire into the graphite of the pencil, which then transmits the electricity into the salt water. The electricity then splits each water molecule into its basic components: two atoms of hydrogen and one atom of oxygen. There are twice as many bubbles on the pencil attached to the negative side of the battery because the hydrogen atoms gather there. Oxygen atoms accumulate on the pencil attached to the positive side of the battery. Pouring Water Sideways Materials A clear plastic drinking cup Cotton twine A sink, bucket or other container A counter top or other surface Some scotch tape Optional: A stack of books Procedure Cut, or have an adult cut a piece of string 3 feet long. Tape one end of the string to the side of the cup near the top. Fill the cup with cold water 2/3 of the way full. Wet the string in the water until it is thoroughly wet. Pass the string over the cup, resting it on the rim of opposite side. Find a place where you can do the experiment. You want some sort of container to catch the water, and a place to rest the cup that is about a foot above the ground. One good way to do this is to use a sink with a counter around it- you can place the cup on a stack of books, perhaps. This is not necessary, but it helps to keep your hands steady during the experiment. Place the cup (and the stack of books) about two feet away from the sink or bucket where the water will be poured into. Place the other end of the string in a sink. You may want to place paper towels between the cup and the sink to catch any accidental spills. If you aren‟t using books, lift the cup about a foot off the ground. Hold the string in the sink and pull it tight. Very carefully, begin to slowly pour the water out of the cup. Keep the string tight! Make sure to hold the cup steady and keep an even trickle of water. This is where the books are helpful, because you can rest the bottom of the cup on the books. If you did it right, no water will spill out and hit the table! The Scientific Explanation This experiment works because of the “adhesive” and “cohesive” properties of water. Water has a slight charge to it, and because of this, it likes to stick to other things that have a charge. Water likes to stick to other surfaces, which is called adhesion, and also sticks to other water, which is cohesion. The water the string was wet with sticks to the string. The water you pour down the string also will stick to the string and the water in the string. Together, the attraction between the water and the string and the water and the water is enough to overcome the gravity that is pulling the water down. Surface Tension Materials 1 penny 1 eyedropper / pipette 1 foam cup Concentrated dish soap spoon paper towels tap water Procedure Wash the penny with soap & water, then dry. Fill the cup with tap water. Fill the eyedropper / pipette from the cup. Hold the dropper above the penny and steadily add drops one at a time, counting each drop as it falls. Stop adding water when it overflows the edges of the penny and record the number of drops required. Add 1 drop of dish soap to the cup of water and dissolve by stirring with the spoon. Dry off the penny, then repeat steps 3-5 using the new soapy water solution. What do you observe? Does anything different happen when the soapy water is used instead of regular water? The Scientific Explanation Water molecules consist of three atoms: 1 oxygen and 2 hydrogen. However, because the oxygen atoms attract electrons more strongly than hydrogen atoms do, this causes the hydrogen ends to have a positive partial charge and the oxygen atom a negative partial charge. A compound such as water that has these kinds of weak partial charges is polarized. The molecules act like magnets, sticking to each other. The weak attractions that cause this are called hydrogen bonds. When water alone is added to the penny, the water molecules are attracted to each other, causing surface tension, which makes the water resist overflowing the edges of the penny. However, when soap is added, it forms a layer on the surface of the water that interferes with the intermolecular forces, causing the water molecules to be attracted to each other less, decreasing surface tension and thus, the amount of water needed to overflow the edges. Lifting an Ice Cube Materials Plastic Cup Water Table salt (NaCl) A piece of string (about one ft. long) Procedure Fill your cup about ¾ full with cold tap water. Stir until the salt dissolves. Place the middle of the string over the ice cube. Press the string onto the ice cube so that the string stays on top of the ice cube. Pour enough salt onto the point where the string touches the ice cube so that the string is covered in a coat of salt (about three pinches) Wait about 20 seconds. Lift the string. What happens? The Scientific Explanation Water turns into ice at a temperature of 32°F or 0°C; however, salt causes water to have a lower freezing point. So, when salt is sprinkled onto the ice cube, it melts some of the ice. The liquid (water) left on top of the ice cube is still close to 0°C. As the salt fully dissolves into the water in the cup, the water on top of the ice starts to refreeze. As it refreezes, the string also gets frozen onto the ice cube. That which doth not mix Materials Plastic cup Olive Oil Cold water Procedure Pour the olive oil into the plastic cup so that the cup is nearly half filled. Pour the cold water on top of the olive oil until it almost reaches the top of the cup. Swirl the cup in a circular way and let it sit for ten minutes. Empty the plastic cup into the drain of a sink and throw out the cup. What do you observe? Do the two liquids mix? What happens as the two liquids are left to sit? The Scientific Explanation There are two reasons why olive oil and water do not mix. First, oil is lighter than water, so when the heavier water is poured in it pushes the oil up. This is because water has a higher density. Second, water molecules tend to attract each other because they are charged. Olive oil molecules are not charged at all, so the water will try to stick together as much as possible. Sink-a-Dime Materials: Two identical drinking glasses One dime Large tub filled with big enough water to submerge both glass cups on their sides at the same time Towel (for any spills) Procedure: Fill the large tub with water Submerge both glass cups in the tub Press the rims of the cups together While keeping the rims together, take out the glasses and set them the towel, with one glass resting freely on top of the other Gently tap the top cup to slide it off of the bottom cup until there is a space big enough to slide the dime into the bottom cup Insert the dime into the bottom cup Scientific Explanation The water in the top glass didn‟t spill out all over the table because water has a certain property called surface tension. Surface Tension is the name given to the cohesion between molecules of a liquid at its surface. Cohesion is the attraction of molecules of a liquid to other molecules of the same liquid. The molecules in a volume of water pull on the other molecules of water closest to them, keeping them grouped together. The molecules on the surface pull on each other, creating something like a sac that keeps all of the molecules together. The bond angle, angle at which atoms are bonded together in a molecule, of water is special and creates strong cohesion between water molecules. It also creates strong surface tension. It is strong enough to hold all the water in the glass cup without it spilling out. There are many other experiments demonstrating surface tension. One of them includes counting the drops of water that may be dropped on the top of a coin before the water spills over. Air Takes Up Space Materials paper towels 1 medium sized clear plastic bowl/container 1 tissue 1 clear glass 1 ping pong ball Procedure Fill the clear plastic container/bowl almost to the brim with water. Place the ping pong ball into the clear glass. Overturn the glass with the ping pong ball in side of it onto the water. Press the glass downwards a few inches. What do you notice about the ping pong ball? What do you think is inside the glass? Remove the glass and ping pong ball from the container. Dry the glass thoroughly with a paper towel. Crumple up the tissue and put it into the bottom of the glass so it stays. Overturn the glass into the water-filled container. Press the glass downwards a few inches into the water, making sure that the tissue is still lodged within the glass. Remove the glass from the water, and keep it turned over as you dry the outside of the glass with a paper towel. Carefully take out the tissue. What do you notice about it? What does this tell you about what was inside the submerged glass? The Scientific Explanation Air, just like any other form of matter, takes up space. We can see how air maintains space when we observe how the insides of containers behave when submerged in water; for example, when an upside down glass that has air in it is pushed under water, the inside of the glass doesn‟t fill up with liquid. This is because the air that is already in the container when it is turned over stays inside of the container and pushes against the water that is trying to get in. This is called air pressure, and it comes from air molecules taking up space. Gravity-free Water Materials 1 1 1 1 glass cup sink index card (4” x6” ) shallow, clear glass or plastic bowl (not metal) Procedure 1. Place the index card on top of the cup and flip it upside down. 2. What happens to the index card when it is flipped? 3. Filled the cup with water so that the water is at the brim. This should be done at a sink because the water can spill while it is being filled. 4. Place the index card over the top of the cup. 5. Press down on the card so it is touching the water in every part of the index card. 6. Flip the cup upside down again. 7. What happened to the water? Why did the water not come out of the cup and spill on the floor? The Scientific Explanation The water is held in the cup the second time because of air pressure. The force of air pressure is shared through every part of the air and pushes out in every direction. It pushes back against any force, but we normally can‟t feel this. The weight of the water is low enough so that the water is held up by the air Under Pressure? Materials 1 plastic 1 liter soda bottle 1 fun size snickers candy bar in wrapper About 1 liter of non-carbonated water Procedure Remove the label and top of the bottle Fill the bottle with water until it reaches the top of the bottle. Push the snickers bar through the opening of the bottle. This will be a tight fit, but it is possible. Tightly screw the bottle cap on. Squeeze the sides of the bottle. What happens to the snickers bar? What happens to the wrapper of the snickers bar? The Scientific Explanation The physics of this experiment are based on the science used by Cartesian divers. The snickers bar has a small amount of air in the wrapper which causes it to be neutrally buoyant. This means that it barely floats below the surface of the water and therefore the snickers represents the diver. When pressure is applied on the sides of the bottle, the water is able to evenly carry this pressure to the diver. This causes the air within the wrapper to compress, resulting in a higher density and less buoyancy. The diver proceeds to sink. Capillary Action Materials Tap water (hot and cold) 4 cups plastic 10 ounce cups 2 Paper towel sheets Stop watch or timer Procedure Fill one plastic cup with 8 ounces of cold water. Place an empty cup ½ inch away. Fill another cup with 8 ounces of hot water. Place the other empty cup ½ inch away. Roll each paper towel sheet separately into rope-like wicks. Place one end of a rolled paper towel into the cold water and the other end into the empty cup. Place one end of the other rolled paper towel into the hot water and the other end into the second empty cup. Time the two cups to see which transfers water into the empty cup the fastest. What did you notice? The Scientific Explanation The water transfers between the two cups because of pores in the paper towels. Theses air holes are called capillaries. When the pores fill with water, the fluid progresses through the wick until gravity can overcome the intermolecular forces of the water molecules. The hot water travels faster than the cold water because heat causes the kinetic energy of the water molecules to increase, speeding them up. If left for an extended period of time, the water in both cups will transfer into the empty ones until equilibrium is reached (the level will be the same in all four cups). Air Currents: Heat Rises Materials votive candle matches tall plastic cylinder (one open end) Procedure Set a votive candle on a flat table top and light it. Place a clear plastic tube with a small hole in the top over the candle and wait 15 seconds. Notice how the flame has gotten smaller. Lift the tube a little so that one side of the bottom is still touching the table. Notice how the flame grows. The Scientific Explanation We know that fire needs oxygen in order to stay lit. With that, you might think that the small hole in the top of the tube provides an inlet of oxygen to feed the flame and sustain it; however, this assumption neglects one key factor which is the point of this experiment. Heat rises. Why? The difference between hot air and cooler air is the amount of energy the atoms have. Hot air molecules have more energy (making them hot) and the more energy the atoms have, the faster they move around thus taking up more space even though there‟s the same amount of atoms. This makes it less dense and lower densities “float” on top of higher densities. Now that we know why heat rises, we can understand that the rising heat from the candle in the cylinder of this experiment flows through the hole in the top. This air current prevents enough air from entering into the tube through the hole. This means that the flame will only stay lit until the oxygen in the tube runs out and then it will go out. Lifting the tube allowed air to flow up into the tube, rather than fighting through the small hole and it fed the flame to make it grow again. Air Pressure Materials 1 potato 2 straws Procedure Take the straw and make sure that the top hole that will not be injected into the potato is not covered. Insert the other end of the straw into the potato. Can it be inserted into the potato? Remove the first straw from the potato and take the second straw. Take the second straw and this time make sure that the top is covered. Inject this straw into the potato. Can this straw go through the surface of the potato? Remove this straw from the potato. The Scientific Explanation Air pressure is the main factor that affects this experiment. When trying to insert the first straw into the potato (when the hole is not covered), it will not go into the potato. This is because the air molecules freely pass through the straw and do not put pressure on the potato. The straw alone is unable to break through the surface of the potato. When the hole is covered on the straw, the air molecules inside are compressed, increasing the pressure. This increase in pressure puts more pressure on the potato when trying to insert it into the potato. The pressure keeps building up until eventually the straw has to go through the surface of the potato due to an overload in pressure. Candles and Air Pressure Materials Pan Water 3 birthday candles Aluminum foil Clear glass cup Matches Procedure Fill pan with just enough water to cover the bottom. Mold aluminum foil holder for candle. Place candle and holder in the pan with the water. Light the candle. Place glass upside down over candle. Observe the changing water levels within the glass. Once water is absorbed measure height of water within the glass. Repeat step 2-7 twice adding an additional candle each time. The Scientific Explanation Fire needs oxygen to burn. When the candle is covered with the glass, it is no longer receiving that required oxygen. This creates a lower concentration of pressure inside of the cup. The pressure outside the cup can then push the water up. The dying candle flame is also responsible because it cools the air. Hot air expands and cold air contracts. If the air contracts, there will be more space in the cup that the water can consequently fill. Humpty Dumpty Had a Great Fall… Materials 1 hard-boiled egg small piece of scrap paper matches glass milk bottle Procedure Peel the egg. Light a small piece of paper with a match and drop the paper into the milk bottle. Place the peeled egg on top of the bottle and watch what happens. The Scientific Explanation Air molecules move farther apart when they are heated and this causes air to expand. While the fire is burning in the bottle without the egg on top, air is allowed to expand and escape. When the egg is placed on top, it traps the expanded air. Air condenses when it cools. As the air condenses, space needs to be filled inside the bottle and so a vacuum is created. The egg is pulled into the vacuum and falls into the bottle. Oobleck Materials 1 sheet of newspaper 1 gallon-sized Ziploc bag 1/4 cup water 1 plastic spoon 1/3 cup cornstarch 1 magnifying glass (optional) Procedure Spread the newspaper out so that you don‟t make a mess! Take the 1/3 cup of cornstarch and put it into the Ziploc bag Now add the 1/4 cup of water and add it to the Ziploc bag Take the spoon and mix the cornstarch-water mixture until it becomes gooey. Close the Ziploc bag. Take your fist and punch the Ziploc bag with the solution. Don‟t hurt yourself! Use a magnifying glass…what do you see? Is this a solid or a liquid? Take your finger and jab it (without hurting yourself!) into the solution. What do you see (use a magnifying glass)? Is this a solid or a liquid? Take your finger and dip it slowly into the Ziploc bag solution. What do you see (use a magnifying glass)? Is this a solid or a liquid? The Scientific Explanation The substance that it formed is sometimes called a „so-quid‟ because it displays properties of both solids and liquids. Oobleck is actually a special type of liquid in which all parts of the substance are not flowing at an equal rate. Because the viscosity of the liquid is different, it sometimes has qualities of being a solid and liquid. Oobleck Materials 1 ½ cups cornstarch 1 cup warm water Shallow Plastic container Procedure To create the oobleck, mix the cornstarch and the warm water, in the plastic container, until all the cornstarch has dissolved in the water. Punch the oobleck and record what happens. Does your fist sink into the oobleck at all? Next, put your hand on top of the oobleck and allow it to sink in, then try to take your hand out of the oobleck quickly. Why do you think you are able to sink into it this time? Using your finger, cut a line in the oobleck. Look through a magnifying glass as the oobleck re-forms itself. What did the oobleck look like when you initially cut it? How did that shape change as the oobleck returned to its previous shape? Roll the oobleck into a ball. Can you make it into a round shape? Hold the ball in your hands for a little while. What happens to the shape? The Scientific Explanation As you saw from the experiment, oobleck acts like a solid when you work with it quickly, and acts like a liquid when you work slowly. The reason for this is because of the molecules that make up cornstarch. Molecules are the building blocks of most substances and are too tiny to see with your eyes or even a magnifying glass. The molecules in the cornstarch are starches called amylose. The amylose is made of long chains of atoms, which are even smaller than molecules. When you mix the cornstarch with the water, the amylose molecules get all mixed up in the water. When you put pressure on the water quickly, the molecules get all tangled up and don‟t let your hand through. When you put pressure on the oobleck slowly, the amylose molecules are able to move away and let your hand through. This makes the oobleck feel more like a solid. Cornstarch, Water, and Oobleck materials Measuring cup (1/2 & 1 cup) Cornstarch (2 cups) Water (1/2 cup) Large container or mixing bowl Spoon 3 Plastic baggies (re-sealable) Procedure Pour 2 cups of cornstarch into the mixing container. Pour ½ cup of water into the mixing container. Stir mixture with a spoon until it is a consistent fluid. Scoop the putty into three separate baggies. Seal the baggies shut. Pass out the baggies. The Scientific Explanation Oobleck is a perfect example of a non-newtonian fluid. NonNewtonian fluids are thicker in some areas and thinner in others. Oobleck is made up of long chains of atoms. These chains are called polymers. Although the polymers are able to slide past each other, it takes a long time for them to do so. If the oobleck is left alone, it will flow like a liquid. However, if it is hit, the polymer chains will become tangled, and the oobleck will appear to be solid. CO2 Fire Extinguisher Materials: 1 liter volume glass bowl 3 tbsp baking soda Two tea light candles Matches (or a lighter) 1/8 cup white vinegar Paper Towels Procedure: Pour the 3 tbsp of baking soda into the bottom of the bowl. Shake the bowl in a clockwise motion to evenly distribute the baking soda across the bottom. Place the two candles, wick side up into the bowl as close to the center as possible. Light the two candles and wait for about 10 seconds. Pour the vinegar into the bowl (not onto the candles, just the baking soda) Observe what happens to the flames. The Scientific Explanation: Reacting baking soda and vinegar (commonly used in “volcano” type experiments) produces the CO2 , or (carbon dioxide) gas. This gas is heavier than air, and therefore it sinks to the bottom of the bowl, replacing the oxygen that once occupied that space. This new CO2 gas puts out the flame because flames need oxygen to burn – oxygen that was displaced by the CO2. Shrinking Water Bottle Materials 1 empty .5 liter water bottle 1/2 cup of water thermometer any water heating device Procedure Heat up the half-cup of water until it reaches a temperature of 152 degrees Fahrenheit (67 degrees Celsius), so that the water starts to steam. Be careful when handling the hot water; you may need an adult to help you. Allow the water to cool if it is too hot to handle, and then pour it into the empty bottle. Allow steam to collect in the bottle for 10 seconds. Unscrew the cap for a couple of seconds to let out the steam, and then quickly replace the cap. Allow the water inside the bottle to cool for ten minutes. Observe the bottle as it cools and record anything you notice about the bottle‟s shape. The Scientific Explanation If you have ever seen party balloons left out overnight, you may notice that the balloons are smaller in the morning. You may even notice the balloons becoming larger during the day. When substances are warmed, the particles in those substances expand, and take up more space. As the objects cool the particles take up less space. This experiment shows a similar situation using a water bottle. When you release the steam from the bottle, there is less air inside the bottle, and the particles are just moving around quickly enough to keep the bottle full. As the water cools, the air inside the bottle takes up less space, and the plastic contracts. If you were to reheat the bottle, it would regain its original shape. Friction ! Materials 2 large telephone books such as Yellowbooks Procedure Work in pairs. Put the Yellowbooks next to each other. Layer the pages of one Yellowbook into the second Yellowbook one page apart. Continue layering as many pages as possible (200 pages would be enough to overcome the pulling power of 2 children). Lift the Yellowbooks and try to pull them apart. Did the Yellowbooks give in? The Scientific Explanation Friction is a force that does not allow an object, which touches another object, to move freely. Friction between the pages does not allow the books to be pulled apart. The more pages are interlocked, the greater the area of contact between the Yellowbooks. If all the pages were put on top of each other one page apart, it would take over 8000 lb of force to pull them apart, which is equal to 2 tanks pulling with full force. If only a couple of pages were put together, friction would be much less, allowing the pages to be pulled apart. Sliding Vs. Rolling Friction Materials Spring Scale (measures force) Reading Book (about 3 pds) White Lined Paper 8 Thick Markers Masking Tape Plastic Ruler Scissors Pencil String Procedure Gather the materials for the experiment (small reading book, string, duck tape, scissors, spring force scale, pencil, paper, 8 thick markers and ruler) on a table. Make a chart on the piece of paper with the pencil. Make two columns with “Sliding” as one title and “Rolling” as another title. Each column should have two rows (title -> data). Lay book face down on the table. Measure a 4 inch piece of string with a ruler and then cut the piece of string with scissors. Measure a 1 inch piece of duck tape with a ruler and then cut the piece of tape off with scissors. Tape 4 inch piece of string to the book so the edge of the string is a half of an inch away from the edge of the book. The rest of the 3 and half inches of string should be hanging off the edge of the book. Make a small loop on the edge of the string hanging off the book with a standard knot. Hook the bottom hook of the spring scale to the knot of string. Pull gently on the top part of the spring scale as you pull the book across the table. As you are sliding the book across the table, read the amount of force (in Newtons (N)) on the spring scale. This is the amount of force necessary to slide the book across the table. Record the force in the data column under “Sliding”. Now complete the same procedure but with the 8 markers spaced evenly under the book As you roll the book on the markers read the amount of force (in Newtons (N)) on the spring scale. This is the amount of force necessary to role the book across the table. Record the force in the data column under “Rolling”. Compare and Conclude: Which method of moving the book took less force? Generalize: For any object, is it easier to slide or role the object across a flat surface? The Scientific Explanation The focus of this experiment is on the advantages of rolling an object rather than sliding an object. To get an object moving a force is needed. At the same time, friction is pointing in the opposite direction of the motion direction/force of the object. Friction is the resisting force to the motion of the object. This project focuses on kinetic friction and the force it takes to keep the object in motion. The more kinetic friction the more force needed to keep an object moving. Rolling an object is easier than sliding an object because there is less force required to roll an object than slide an object. This is because there is less kinetic friction involved with wheels and rollers than sliding surface to surface. Not as much force is needed to keep the object mo Burning Money WARNING: Burning U.S. currency is against the law. The bills used in this experiment should not sustain damage if the procedure is done correctly, but proceed at your own risk. Materials 2 disposable aluminum pie pans A small bottle of isopropyl (rubbing) alcohol Measuring spoons or cups A small candle Matches Metal tongs U.S. $1 bill (other denominations or “linen” paper will also work) Procedure (Note that this is made for teachers to give as a demonstration; it is not safe for students to conduct) Prepare a solution of 50% isopropyl alcohol and 50% water, keeping in mind that the alcohol from the bottle is likely to be partially diluted with water already. You will only need enough solution to cover the bottom of one pie tin to conduct multiple demonstrations. Set the pie tins up side by side with the alcohol solution in one of them and the candle in the other. Place the dollar bill flat in the alcohol solution and let it soak until saturated; this should not take more than 15 seconds. While the bill is soaking, put the candle in the center of the empty pie tin and use the matches to light it (be wary of setting the alcohol solution on fire). After the bill is soaked, use the tongs to pick up the bill and hold it over the alcohol solution for a few seconds to let the excess solution drip off. When the bill has mostly stopped dripping, swing it carefully over to the candle and touch a corner to the flame. The flames will grow rapidly and burn for a couple seconds once ignited, then quickly subside. Take care to ensure that the flames completely extinguish. It will take around 5 seconds from lighting the flames until they should extinguish, any longer and the bill itself is probably on fire and should be extinguished. The Scientific Explanation The reaction of the alcohol and oxygen in this experiment is a combustion reaction represented by the following equation: C2H5OH + 4 O2 -> 2 CO2 + 3 H2O + energy The alcohol has a high vapor pressure relative to water and thus moves towards the top of the solution, effectively coating the water, which is in turn coating the bill. When the alcohol combusts, the heat energy it releases is not enough to evaporate the water. The bill is insulated from the heat by the water and does not reach a high enough temperature to combust. When all of the alcohol has combusted, the waterlogged bill is unharmed. In simple terms, the water coats the bill and insulates it from the alcohol. Since water does not burn, the money will not either even though the alcohol around it will. The flames you see are the alcohol burning, not the money. Rubber Band Car Materials Corrugated cardboard 4 CDs 4 ¼ inch washers 2 wooden skewers Poster putty Rubber band Scissors Ruler Procedure Cut a five inch by six inch rectangle from the cardboard. Cut a notch 2 inches wide and 1 1/2 inches deep in one of the 5 inch sides of the foam board rectangle. This notched end will be the front of the rubber band car. Slide a wooden skewer through the cardboard near front of the car. Slide another wooden skewer was slid through the back of the car. Make sure that the skewers are parallel to the front edge of the car and stick out approximately the same distance on either side of the car. Twist the skewers around until they are able to rotate freely. Hold a washer to the center of a CD and slide them onto the end of a skewer. Leave a little room between the CD and the cardboard. Use poster putty to hold the washer to the CD and to secure the whole wheel to the axle. Glue or tape a rubber band to the cardboard a little bit behind the notch. Stretch the other end of the rubber band over the front axle and the twist the wheels until the rubber band is tight (but not too tight – you don‟t want it to snap). Place the car on the ground and release the wheels. Watch the car move forward! The Scientific Explanation Potential energy is stored energy, while kinetic energy is motion. As you wind the rubber band around the wheels, potential energy is stored in the rubber band. When the rubber band is released and unwinds, the stored potential energy is converted to kinetic energy and the car is propelled forward. Laws of “Attraction” Materials A plastic comb or ruler A faucet with running water A test subject with hair (it can be yourself!) Procedure First, go to a sink and turn the cold knob until a slow and steady stream of water is pouring out. Then, take the plastic ruler and run it through your hair twenty to thirty times Now, making sure not to touch the ruler to anything, slowly move the edge of the ruler, which is farthest from your hand, towards the running water that is near the bottom of the sink. Watch as the water starts to bend toward the ruler! Why do you think that works? The Scientific Explanation Well, everything that you see around you is made of lots and lots of tiny little things called atoms. Each of these atoms has protons, which are positively charged, and electrons, which are negatively charged. When the atoms of an object have more electrons, then the object also has a negative charge. When the atoms have more protons, then the object is positively charged. Things that have opposite charges are attracted to each other. When you run the ruler through your hair, it makes some of the electrons in your hair “jump” to the ruler. That causes the ruler have more electrons, which means it has a negative charge. Water is made of groups of two hydrogen atoms and an oxygen atom which have combined to make molecules. Each water molecule has a positively charged side near the hydrogen and a negatively charged side near the oxygen. The positive sides of the water molecules are attracted to negatively charged things, like the ruler. Because of this attraction, the water bends when the ruler moves closer to it. Electrified Dice Materials Glass sheet, about 8 inches by 10 inches Two thick books Five foam cubes, the size of dice Felt-tip pen or permanent marker Piece of wool Procedure Place two books on the table, about 8 inches apart Place the glass sheet between the pages of the book so that it is about 1in above the table Draw dots on the foam cubes using a felt tip pen or permanent marker in order to make them look like dice Place the “dice” underneath the glass Rub a piece of wool back and forth on the surface of the glass Notice the movement of the dice even after you stop rubbing the glass The Scientific Explanation When you rub the wool on the glass, you are generating what is called static electricity. This causes a charge to build up on the glass. The foam dice don‟t have a charge, but they are still attracted to the charged glass. This attraction causes the dice to have an excited state, which makes them move around. Even after you stop rubbing the wool over the glass, the charge stays for some time. Bending Water Materials Latex balloon Faucet with running tap water Stop watch or a clock with the seconds hand A volunteer with long hair Procedure Blow up the latex balloon Using a volunteer from class, rub the balloon in his/her hair for about 45 seconds. Make sure the balloon doesn‟t touch anything except the hand it is held in Turn on a faucet so tap water is running in a thin stream Bring the side of the balloon that was rubbed in hair close to the water and watch as the water bends towards the balloon Does the water bend more if the balloon is closer or farther away from the water? What if the stream of water is thicker? What if the balloon was never rubbed in hair? Always make sure to check for latex allergies before bring a latex balloon into class. If there is a latex allergy, a hard plastic comb can be used instead. The Scientific Explanation Some objects, such as magnets, have a charge. This means that they attract other charged objects, such as other magnets. This explains why if you put two magnets near each other, they will pull together. Water molecules are like magnets. They are attracted to each other. This explains why water forms droplets. Balloons are not normally charged, so if you bring a balloon that wasn‟t rubbed in hair near water, nothing happens. Hair has the potential to charge a balloon. When you rubbed the balloon in your classmate‟s hair, the balloon became charged just like a magnet or a molecule of water. When the charged balloon was held near the water, the water and balloon were attracted to each other. Because you were holding on the balloon, it wasn‟t able to pull towards the water, but the water was easily pulled towards the balloon. Fun with Static Electricity Materials 1 tissue 1 Piece of printer paper a pair of scissors a ruler any one of the following materials: cotton cloth, wool cloth, nylon cloth, animal fur, human hair a clock/watch/timer Procedure Cut 3 squares out of the tissue. One .5 by .5 inch, one 1 by 1 inch, and one 2 by 2 inch. Now, cut 3 square of the same size out of the piece of printer paper. Place the squares onto a dry surface. Make sure that they are at least one inch apart. Rub the comb against the cloth/fur/hair for 10 seconds. Immediately touch the comb to the .5 by .5 inch tissue square and lift the comb into the air. Record how many seconds that the tissue remains in the air. Rub the comb against the cloth/fur/hair for another 10 seconds. Now, touch the comb to the 1 by 1 inch tissue and lift the comb. Record how many seconds that the tissue remains in the air. Repeat this process with the 2 by 2 inch tissue square and the various sized printer paper squares. What effects did the size and type of paper have on the time that the paper squares remained in the air? The Scientific Explanation All objects are made up of tiny particles called atoms. In each atom, there are even smaller particles called protons and electron. Atoms of different objects can exchange electrons, which causes a change in the balance of protons and electrons. An object that has more protons than electrons has a positive charge, and an object that has more electrons than neutrons has a negative charge, and n object that has an equal number of protons and electrons it has a no charge and is called neutral. Objects with like charges repel each other, objects with opposite charges repel each other, and an object with any charge will attract an object with no charge (neutral). In this experiment, the comb was given a charge when it was rubbed with another material (whether it was positive or negative depends on the material that the comb was rubbed against). When the comb was charged, it is said to have static (not moving) electricity because the comb had electricity from the charging, but the electricity was not allowed to flow because the comb is an insulator (an object that does not allow the flow of electricity). Because the comb was charged and the paper was neutral, the comb was able to pick up the paper through electrical attraction. Charge for Cheerios! Materials scissors thread 10-20 Cheerios or other doughnut-shaped cereal balloon sweater tape Procedure Measure and cut a twelve-inch piece of thread and tie one end of it through a piece of cereal. Tape the other end of the string to a table so that it does not hang near any other objects Blow up a balloon and rub it against a sweater for one or two minutes to produce static electricity around the balloon. Lift the balloon and slowly move it towards the piece of cereal that is hanging off the side of the table. Watch the piece of cereal. Does it move towards the balloon? Hold the balloon in place until the piece of cereal moves away from the balloon on its own. Move the balloon near t he piece of cereal once again and observe the piece of cereal. It moves away from the balloon this time, right? The Scientific Explanation The transfer of electrons, or negatively charged particles, takes place within a small electrical current, which produces a very small electric shock. When you generate static electricity between the sweater and the balloon an electric shock is produced and electrons are transferred from the sweater to the balloon. This transfer of electrons results in the balloon having a greater number of electrons than it previously had, giving it a new negative charge. When you move the balloon towards the piece of cereal, electrons are once again transferred to the cereal, which is why it is immediately attracted to the balloon. However, once the piece of cereal gains a certain number of electrons it then has the same charge as the balloon and the two objects repel each other. Magical Magnetism Materials 60-70 paperclips 1 bar magnet 1 horseshoe magnet 1 circular magnet 1 inch piece of magnetic tape Procedure Lay the paper clips out on the table. Hold the bar magnet above the table. Hold paperclips against the magnet until the paper clip stays. Put more paperclips on the magnet until no more paperclips will stay. Take the paperclips off of the magnet. Count the number of paperclips and write it down. Then, repeat steps 1-7 for the other magnets. Light fro ht The Scientific Explanation Magnets have two poles, north and south. North poles repel north poles and attract towards south poles. South poles repel south poles and attract north poles. Magnets produce a magnetic field that extends out from the north pole and curves back towards the south pole. Within its magnetic field, a magnet can affect other materials. For example it can hold paper clips when they are within the magnetic field. As a further experiment hold a magnet under a piece of paper and pour iron filings on the paper. The filings will be pushed into a pattern. The pattern the filings are in shows the edge of the magnet‟s magnetic field. Make an Electromagnet Materials An iron nail, preferably 6” or longer A spool of insulated wire Scotch tape Wire strippers AA battery Paper clips or other small metal objects Procedure Strip the insulation from the end of the wire, and tape it to the head end of the nail, keeping some length of wire between the end of the wire and the nail. Begin coiling the wire down the nail. Try to wrap the coils together as tightly as possible. When you get close to the tip of the nail, start coiling the wire back up the nail (it‟s okay to make coils on top of each other). Finish coiling when you make 2 or 3 layers of coils. Tape the final coil down and cut the wire from the spool. Make sure you have enough wire to connect both ends to the battery. Strip the insulation from this end as well. Tape the ends of the wire to the ends of the battery. If the battery starts to get very hot, remove one end from the battery for a while. Move the tip of the nail near the paper clips. They should be magnetically attracted to the nail. Experiment: a. What happens when you use more layers of coils (4, 5, 6, or more)? b. What happens when you use fewer layers of coils (1 or 2)? c. What happens when you switch which ends are attached to which ends of the battery? The Scientific Explanation Magnetism is caused when electrons move. Electrons are spinning in all objects, but a magnetic field is only created when they spin in the same direction. When this is the case, the object is called a permanent magnet. Electromagnets, on the other hand, are formed by a coil of wire. When electricity travels through the coil, a large number of electrons are traveling in the same direction, so a magnetic field is formed. This is the case with this experiment. Floating Paper clip Materials String Magnet Scissors Paper clip Scotch tape Clean glass jar with lid Procedure: Take the scissors and string. Cut a piece of string about the length of the jar. Next, tie the string to the paper clip with a simple knot. The string and paper clip should now be a little less than the length of the jar. (It may be necessary to cut off some of the extra string). Take a piece of tape and wrap it around the end of the string. Take a second piece and make it double-sided (so both sides are sticky). Place one side on the bottom of the jar. Place the string and paper clip onto the other sticky side of the tape on the bottom of the jar. Take the magnet and tape it to the lid of the jar. Now, secure the lid and turn the jar upside down. The string hangs down near the magnet. Now turn it right side up again and notice what happens to the string. It will be suspended in mid-air. The Scientific Explanation The paper clip, as you saw, looks like it is floating in mid-air. This is due to the force called magnetism. Objects have a magnetic field around them. This is an area around an object that is created by an electric current. The magnet has a magnetic field that attracts the paper clip. The magnet has both a north and south pole, which are just the opposite ends of the magnet. If you had a second magnet, the north pole of that magnet would attract the south pole of the first magnet, and the south pole of the second magnet would attract the north pole of the first magnet. Two north poles would not be attracted to each other. Also, two south poles would not be attracted to each other. The paper clip does not stick directly to the magnet only because the string holds it back. Somewhere Over the Rainbow Materials: a small mirror a piece of white paper or cardboard water (H2O a container: a large shallow bowl or pan a flashlight Procedure: Fill up the pan or bowl with water until the water is about an inch from the container‟s rim. Place the container on a flat surface like a table or the floor. Turn off the lights in the room and close the blinds if possible. One person should hold the mirror in the water at about a 45o angle. A second person should hold the white paper in front of and above the container. Another person should turn on the flashlight and shine it on the mirror in such a way that the reflection of the light shines onto the piece of paper. Notice the rainbow that appears on the piece of paper. The Scientific Explanation Many people have seen a prism. A prism splits light into the colors of the rainbow. In this experiment, light is passing from the water to air, which causes its speed and direction to change. This is called refraction. It causes the colors of the rainbow to become apparent. Sky in a Jar Materials a clear, straight-sided drinking glass or jar 1 cup of water (H2O) 1 teaspoon milk flashlight measuring spoons a darkened room Procedure Fill the glass or jar with 1 cup of water. Add 1 teaspoon of milk and stir until the milk and water are thoroughly mixed. Turn off the lights in the room and shut the blinds if possible or bring the glass and flashlight into another room. Hold the flashlight above the surface of the water with the light shining on the water and observe the water in the glass from the side. What color is the mixture?Hold the flashlight to the side of the glass and look through the water directly at the light. What color do you see now? Put the flashlight under the glass and look down into the water from the top. How did the color change? The Scientific Explanation The small particles of milk suspended in the water scattered the light from the flashlight, like the dust particles in the air scatter sunlight. When the light shines on the top of the glass, the water looks blue because you see blue light scattered by the milk. When you look through the water directly at the light, it appears red because the blue light hits the cup at an angle and has more water to pass through. This scatters the blue light more, but the red light travels straight through the water. Blue light has a shorter wavelength than red light. In the sky, the longer wavelengths pass right through all particles. The shorter wavelengths, like blue light, are scattered by the particles and reflected back to earth at all different angles. When the light is scattered in all different directions, it can be seen from everyone on earth which makes the sky look blue. Making a Rainbow! Materials Flashlight with Battery Small Mirror White Wall or several sheets of white paper and tape Water Container with large base(cereal bowl/baking pan) Procedure Place a container near a white wall (if you are using paper tape white paper on to the wall.) Take the container and you use and fill it with water until it is three quarters of the way full. Take a small mirror and place it in the bowl so some of the mirror is in water and some of it is not. Make sure the mirror is facing away from the wall. Now shine the flashlight so the light is shining on the part of the mirror that is out of the water, and the part of the mirror that is out of the water. Now turn off the lights to the room and close the shades Observe a rainbow on the wall Once you are finished take the mirror out of the bowl and pour the water out of the bowl into a sink. Also turn the flashlight off. The Scientific Explanation A rainbow is normally caused right after there has been a lot of rain and the sun is out. A rainbow is an arc of light that is separated into multiple parallel stripes of color. The water droplets that are still in the air after a rain shower interact with the sun‟s light rays by bending it and reflecting it. This process makes the white light rays the sun gives out into a whole spectrum of colors that is known as a rainbow. The colors of a rainbow are red, orange, yellow, green, blue, indigo, and violet (in that order). In this experiment the same science is being replicated to form a rainbow, and the scientific explanation is the same, except instead of the sun, the light from a flashlight is being bended and reflected by the water in the bowl. The rainbow is then shown on the wall. The Water Drop Microscope Materials Small flashlight, headlamp, or similar Clear plastic container (ex: a Rubbermaid container) Thin piece of metal (aluminum, 1 by 5 inches) Scotch tape Water Anything you want to look at under the microscope Procedure Place the lid of your container upside down on the table, turn on your flashlight, and place your flashlight on top of the lid so that it is aiming straight upward. Enclose the flashlight within the container by lowering the main body of the container over it and attaching it to the lid underneath. Drill a small (3/16 inch) hole in the piece of aluminum centered about a ½ inch from the end of the piece. Bend the aluminum into a right angle 1½ inches from the end the hole was drilled near. Tape one end of the piece of aluminum to the container so that the hole on the other end is centered about 1 inch over the top of the container. Place a drop of water in the hole in the aluminum. The drop will stay there suspended. Notes The aluminum may have to be moved up and down or bent up and down to focus the microscope. Make sure that the light is not too bright or it might make the object being viewed look very blurry. The Scientific Explanation A lens in a microscope works as shown in the image below. They redirect the light that passes through them into one point, and when the light passes that point, it spreads out again. The water drop, when suspended as it is in your water drop microscope, is pulled downward by gravity into the shape of a lens, but does not fall out if the hole because it is held there by the surface tension of the water. Because it is in the same shape as a lens and light can pass easily through water, the drop works just like a lens does. Pendulums Materials Strings measuring 3, 4, & 5 ft Box of paper clips Timer Open doorway Yard stick Masking tape Procedure Mark a line three feet from the doorway. Tie loops at both ends of each string and distribute them equally across the top of doorframe, taping them with the strings hanging down. On each of the bottom loops, place two paperclips. Bring one string back to the line and release it, timing the period. Do this for each of the strings. Add two more paperclips and repeat step 4. Continue adding paperclips and timing the periods until there are eight paperclips on each string. Create a table comparing the weight and period length for each length string. How does weight affect the period? How does length affect period? If you wanted a longer period, would you change length or weight and would you add it or subtract it? The Scientific Explanation Pendulums swing because of gravity. When you release the bob, gravity pulls it down as far as possible. Then the momentum of the bob keeps it swinging up the other side. Because all objects fall at the same rate, the weight of the bob doesn‟t affect the period. But if the pendulum has a longer string, it can travel further and takes longer to complete a period. Definitions Bob- the weight at the end of the pendulum Momentum- the tendency that any moving object has to keep going unless something stops it Period- which is the length of time the bob takes to swing back and forth once