Suggested reading for 2nd quarter: Archimedes and the Door of Science by Jeanne Bendick and
The Mystery of the Periodic Table by Benjamin D. Wiker
Surface Tension
Dialectic Science Lab 4
This lab is for either week 7 or 8
In week 7 of the Grammar Science book, the meniscus is explained and scholars practice
measuring liquid. In Dialectic Science this week, the reason for the meniscus will be explained.
Introduction:
The meniscus is the curved upper surface of a liquid in a tube. The meniscus is formed due to
surface tension. Surface tension is the tension of the surface film of a liquids created by the
attraction of particles in the surface layer by the bulk of the liquid, which tends to minimize
surface area. Soap decreases the surface tension.
Supplies:
Water
Droppers
Waxed paper
Small clear plastic cups 4-5 per scholar or group of scholars
Pepper
Dish soap ½ cup per scholar or group of scholars
Rubbing alcohol
Sewing needles 1 per scholar or group of scholars
Toothpicks 2 per scholar or group of scholars
Tissue paper or klennix (optional)
Pennies
Trays, pie pans or large flat dish to catch spills
Large bowl or bucket to dump waste water (if your classroom does not have a sink)
Teacher Prep: Prepare 1 cup of a soap water mixture by mixing ½ cup of water and ½ cup of
dish soap. Each scholar or group of scholars will need about 1 cup depending on the size of your
plastic cups.
Review: Using the Grammar Science book review what a meniscus is and how to measure it.
Have scholars practice if necessary.
Step 1:
1. Use a dropper to place a couple drops of water onto the waxed paper. Observe the
shape of the drop and record in your lab notebook.
2. Gently tilt the waxed paper so the drops run together. Observe any changes and
record in your lab notebook.
3. Use a dropper to place a couple of drops of the 50/50 soap/water mixture. Observe
the shape of the drop and record in your lab notebook.
4. Gently tilt the waxed paper so the drops run together. Observe any changes and
record in your lab notebook.
Step 2:
1. Place a plastic cup on a tray or pie pan. Fill a clear plastic cup to the rim. Add a
penny to the cup. Observe what happens to the water.
2. Make a hypothesis on how many pennies you can add before the water spills over
the edge of the cup.
3. Observe the shape of the water at the top of the cup.
4. Repeat 1-3 using 50/50 soap/water mixture. Observe the differences and record
your results in your lab notebook.
Step 3:
1. Fill a clean plastic cup about ¾ full of water and gently shake some pepper on the
surface until the surface is mostly covered.
2. Dip the end of a toothpick into the dish soap and touch the toothpick to the surface.
Record your observations in your lab notebook.
3. Fill a clean plastic cup about ¾ full of water and gently shake some pepper on the
surface until the surface is mostly covered.
4. Dip the end of a toothpick into the alcohol and touch the toothpick to the surface.
Record your observations in your lab notebook.
Step 4:
1. Fill a clean plastic cup with water.
2. Drop a needle, point-first into the water and observe what happens to the needle.
3. Carefully lower a needle horizontally into the water and observe what happens to
the needle. If it is difficult to place the needle on the surface of the water, you can
use a small piece of tissue paper to make a ‘hammock’ for the needle as you lower it
to the surface.
4. Use a magnifying glass to examine the surface of the water where the needle is
touching. While the needle is floating, use a dropper to add several drops of the
50/50 soap-water mixture to the surface of the water close to the needle.
5. Record your observations in your lab notebook.
Note: Be sure to use a clean cup for each experiment. If you are reusing cups, make sure to
rinse cups thoroughly. Even a little soap can decrease the surface tension and your
experiments may not show the desired outcome.
It’s a Chemistry Mystery
Dialectic Science Lab 5
This lab is for either week 9 or 10
Introduction: An unknown substance can be identified based on its chemical properties and
physical properties. Chemical test can be performed to determine pH and reactivity with other
chemicals. The pH of a substance can be determined using purple cabbage juice. Please refer
to the Grammar Science book for details. Scholars will conduct chemical test on known
substances. They will then be given an unknown substance to identify using the same chemical
tests.
Supplies:
20 small cups (2 oz) per group of students (clear cups would be best) or test tubes
4 ¼ tsp measuring spoons
Baking soda
Water
Vinegar
Iodine solution (or you can dilute iodine tincture by adding 10 drops of iodine tincture to 100mL
of water)
Cornstarch
Cream of Tarter
Baking powder
Purple cabbage juice
4 droppers
1 sharpie per group
1 unknown sample for each group
Teacher Prep: Prepare an unknown for each group. Add 1/4 tsp of baking soda, cornstarch,
cream of tartar, and baking powder randomly to cups. Label cups A, B, C, etc. and record the
contents of each cup.
Review: Using the grammar science book review acids and bases.
Procedure:
1.
2.
3.
4.
5.
6.
7.
Label cups water, vinegar, iodine, and purple cabbage juice.
Add approximately ¼ tsp of baking soda to each cup.
Record physical appearance.
Add a dropper full of water to the cup labeled water. Record your observations.
Add a dropper full of vinegar to the cup labeled vinegar. Record your observations.
Add a dropper full of iodine to the cup labeled iodine. Record your observations.
Add a dropper full of purple cabbage juice to the cup labeled purple cabbage juice.
Record your observations.
8. Repeat steps 1-7 using approximately ¼ of tsp of cornstarch, cream of tartar or baking
powder instead of baking soda.
9. Scholars will get an unknown sample from their tutor. Repeat steps 1-7 to determine
the identity of the unknown.
Make sure scholars have carefully recorded their observations and instruct them to complete a
lab report using the Scientific Method Lab Report at the back of the Grammar Science book as a
guide.
Physical
Water
Appearance
Baking Soda
Cornstarch
Cream of
Tarter
Baking Powder
Unknown
Sample
Vinegar
Iodine
solution
Purple
Cabbage Juice
Eureka! Archimedes Principle
Dialectic Science Lab 6
This is for either week 11 or 12 and corresponds to week 12 in the Grammar Science book.
Introduction: Archimedes was an ancient Greek mathematician, physicist, engineer, inventor,
and astronomer. Archimedes lived between 287 B.C. and 212 B.C. (this could be added to
scholar’s timelines). There is a story that King Hiero of Syracuse had given gold to a goldsmith
to be made into a crown. King Hiero was suspicious that the goldsmith had not used all the
gold for the crown, but had substituted a cheaper metal. King Hiero knew that the crown
looked like gold and had the same weight as the gold given to the goldsmith, but how could he
be certain that the crown was 100% gold? He asked Archimedes to help him. At first
Archimedes was stumped by this problem. The story goes that as Archimedes was getting into
his bath, he noticed that water overflowed from the tub. Immediately Archimedes figured out
that density determined by water displacement was the solution to their problem. It is said
that he jumped out of this tub and ran straight to the king shouting, “Eureka, eureka!”
The amount of water that an object displaces is related to its density. A pound of feathers is
less dense that a pound of rocks, so if put into a water bath, the feathers will displace less water
than the rocks even though they weigh the same. Silver is less dense than gold, so a pound of
silver displaces less water than a pound of gold. Archimedes found that the crown made for the
king displaced less water than a block of pure gold. Therefore he knew that a less dense metal
such as silver had been mixed into the crown.
Supplies:
Modeling clay – 1 piece per scholar or group of scholars
Cup large enough to hold the modeling clay -1 per scholar or group of scholars
Bowl large enough to hold the cup – 1 per scholar or group of scholars
Paper towel – few per scholar or group and extra for spills
Graduated cylinders – 1 per scholar or group
Kitchen scale – at least 1, but a few would make the lab run smoother.
Cooking oil – 10mL per scholar or group
Corn syrup– 10mL per scholar or group
Calculators – Ask scholars to bring one from home.
Rulers – one per scholar or group
Syringes 10 mL – 3 per scholar or group
water
Procedure:
Part 1:
1. Give each scholar or group a block of modeling clay. Most modeling clay comes as a
brick or cylinder-be careful not to stretch or distort the shape of the clay.
2. Measure the dimension of the clay in centimeters. If it is a rectangular solid, measure
the height, length and width. If it is a cylinder, measure the height and diameter.
3. Have scholars design a crown for King Hiero. Make sure the crown will fit into the cup.
4. Place the cup inside the bowl and fill the cup to the brim with water. You may use a
dropper to make sure the cup is full. If you spill any water into the bowl, use a paper
towel to dry the bowl. Remember from the surface tension lab that a full glass of water
will be rounded over the top of the glass.
5. Carefully drop the crown into the cup of water. The cup will overflow and spill into the
bowl.
6. Carefully use a paper towel to absorb some of the water from the cup without spilling
any into the bowl. Carefully remove the cup from the bowl when enough water has
been absorbed so that the cup can be picked up without spilling.
7. Carefully pour the water from the bowl into a graduated cylinder. Record the volume.
Part 2:
1. Using your measurements from Part 1, Step 2 calculate the volume of the clay.
(cm3 = mL )
a. Rectangular solid – V=lenth * width * height
b. Cylinder – V = π * radius2 * height
2. Compare the values you calculated and measured. Are they the same or different?
Why?
Part 3:
The density of an object plays a part in determining if an object sinks or floats, but buoyancy is
also another factor in determining if an object sinks or floats.
1. The crown made out of modeling clay sank in the cup of water. Have scholars
remove the modeling clay and see if they can form it into a shape that floats.
2. Give scholars time to figure it out. If they need help you can ask them to think of
things that float and to shape their clay as such.
Buoyancy is a law of physics which states that the upward force of an object immersed in a fluid
is equal to the weight of the displaced fluid. This is why giant ship made of steel or concrete,
both which have densities greater than water, can float.
Part 4:
Liquids as well as solid have different densities.
1. Give each scholar or group of scholars a graduated cylinder.
2. Instruct scholars to weigh their cylinders. Record the weight in their lab notebooks.
3. Measure 10 mL of corn syrup using a syringe. Remind scholars how to measure
liquid using the bottom of the meniscus. Add to the graduated cylinder and record
the weight in grams.
4. Measure 10 mL of water using a syringe. Add to the graduated cylinder and record
the weight in grams.
5. Measure 10 mL of cooking oil. Add to the graduated cylinder and record the weight
in grams.
Part
Weight in grams
A
Empty graduated cylinder
B
+ 10 mL of corn syrup
C
+10 mL of water
D
+ 10 mL of oil
6. Calculate the weight of the corn syrup
_____________________ - ____________________ = ______________________
Part B
Part A
weight of 10 mL of corn syrup
7.Calculate the weight of the water
______________________ - ____________________ = _________________________
Part C
Part B
weight of 10 mL of water
8.Calculate the weight of the oil
______________________ - ____________________ = _________________________
Part D
Part C
weight of 10 mL of oil
9.Compare the weight of the liquids to the graduated cylinder. Is the heaviest liquid on the
bottom and the lightest on the top?