North Carolina Science Essential Standards Grade 5 Energy transfer Resource Pack Essential Standard: 5.P.3 Explain how the properties of some materials change as a result of heating and cooling 5.P.3.1 Explain the effects of the transfer of heat (either by direct contact or at a distance) that occurs between objects at different temperatures. (conduction, convection or radiation). 5.P.3.2 Explain how heating and cooling affect some materials and how this relates to their purpose and practical applications. Vertical Strand Maps: http://scnces.ncdpi.wikispaces.net/Strand+Maps Online Atlas map http://strandmaps.dls.ucar.edu/?id=SMS-MAP-2071 http://strandmaps.dls.ucar.edu/?id=SMS-MAP-1341 North Carolina Unpacking: http://scnces.ncdpi.wikispaces.net/Race+to+the+Top+Support+Tools TEACHER KNOWLEDGE BLAST Framework for K-12 Science Education: Energy How is energy transferred and conserved? Interactions of objects can be explained and predicted using the concept of transfer of energy from one object or system of objects to another. The total energy within a defined system changes only by the transfer of energy into or out of the system. PS3.A: DEFINITIONS OF ENERGY What is energy? That there is a single quantity called energy is due to the remarkable fact that a system’s total energy is conserved. Regardless of the quantities of energy transferred between subsystems and stored in various ways within the system, the total energy of a system changes only by the amount of energy transferred into and out of the system. At the macroscopic scale, energy manifests itself in multiple phenomena, such as motion, light, sound, electrical and magnetic fields, and thermal energy. Historically, different units were introduced for the energy present in these different phenomena, and it took some time before the relationships among them were recognized. Energy is best understood at the microscopic scale, at which it can be modeled as either motions of particles or as stored in force fields (electric, magnetic, gravitational) that mediate interactions between particles. This last concept includes electromagnetic radiation, a phenomenon in which energy stored in fields moves across space (light, radio waves) with no supporting matter medium. Motion energy is also called kinetic energy; defined in a given reference frame, it is proportional to the mass of the moving object and grows with the square of its speed. Matter at any temperature above absolute zero contains thermal energy. Thermal energy is the random motion of particles (whether vibrations in solid matter or molecules or free motion in a gas), this energy is distributed among all the particles in a system through collisions and interactions at a distance. In contrast, a sound wave is a moving pattern of particle vibrations that transmits energy through a medium. Electric and magnetic fields also contain energy; any change in the relative positions of charged objects (or in the positions or orientations of magnets) changes the fields between them and thus the amount of energy stored in those fields. When a particle in a molecule of solid matter vibrates, energy is continually being transformed back and forth between the energy of motion and the energy stored in the electric and magnetic fields within the matter. Matter in a stable form minimizes the stored energy in the electric and magnetic fields within it; this defines the equilibrium positions and spacing of the atomic nuclei in a molecule or an extended solid and the form of their combined electron charge distributions (e.g., chemical bonds, metals). Energy stored in fields within a system can also be described as potential energy. For any system where the stored energy depends only on the spatial configuration of the system and not on its history, potential energy is a useful concept (e.g., a massive object above Earth’s surface, a compressed or stretched spring). It is defined as a difference in energy compared to some arbitrary reference configuration of a system. For example, lifting an object increases the stored energy in the gravitational field between that object and Earth (gravitational potential energy) compared to that for the object at Earth’s surface; when the object falls, the stored energy decreases and the object’s kinetic energy increases. When a pendulum swings, some stored energy is transformed into kinetic energy and back again into stored energy during each swing. (In both examples energy is transferred out of the system due to collisions with air and for the pendulum also by friction in its support.) Any change in potential energy is accompanied by changes in other forms of energy within the system, or by energy transfers into or out of the system. Electromagnetic radiation (such as light and X-rays) can be modeled as a wave of changing electric and magnetic fields. At the subatomic scale (i.e., in quantum theory), many phenomena involving electromagnetic radiation (e.g., photoelectric effect) are best modeled as a stream of particles called photons. Electromagnetic radiation from the sun is a major source of energy for life on Earth. The idea that there are different forms of energy, such as thermal energy, mechanical energy, and chemical energy, is misleading, as it implies that the nature of the energy in each of these manifestations is distinct when in fact they all are ultimately, at the atomic scale, some mixture of kinetic energy, stored energy, and radiation. It is likewise misleading to call sound or light a form of energy; they are phenomena that, among their other properties, transfer energy from place to place and between objects. Grade Band Endpoints for PS3.A By the end of grade 2. [Intentionally left blank.] By the end of grade 5. The faster a given object is moving, the more energy it possesses. Energy can be moved from place to place by moving objects or through sound, light, or electric currents. (Boundary: At this grade level, no attempt is made to give a precise or complete definition of energy.) By the end of grade 8. Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed. A system of objects may also contain stored (potential) energy, depending on their relative positions. For example, energy is stored — in gravitational interaction with Earth — when an object is raised, and energy is released when the object falls or is lowered. Energy is also stored in the electric fields between charged particles and the magnetic fields between magnets, and it changes when these objects are moved relative to one another. Stored energy is decreased in some chemical reactions and increased in others. The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and energy transfers by convection, conduction, and radiation (particularly infrared and light). In science, heat is used only for this second meaning; it refers to energy transferred when two objects or systems are at different temperatures. Temperature is a measure of the average kinetic energy of particles of matter. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter present. Science for All Americans: ENERGY TRANSFORMATIONS Energy appears in many forms, including radiation, the motion of bodies, excited states of atoms, and strain within and between molecules. All of these forms are in an important sense equivalent, in that one form can change into another. Most of what goes on in the universe—such as the collapsing and exploding of stars, biological growth and decay, the operation of machines and computers—involves one form of energy being transformed into another. Forms of energy can be described in different ways: Sound energy is chiefly the regular back-and-forth motion of molecules; heat energy is the random motion of molecules; gravitational energy lies in the separation of mutually attracting masses; the energy stored in mechanical strains involves the separation of mutually attracting electric charges. Although the various forms appear very different, each can be measured in a way that makes it possible to keep track of how much of one form is converted into another. Whenever the amount of energy in one place or form diminishes, the amount in another place or form increases by an equivalent amount. Thus, if no energy leaks in or out across the boundaries of a system, the total energy of all the different forms in the system will not change, no matter what kinds of gradual or violent changes actually occur within the system. But energy does tend to leak across boundaries. In particular, transformations of energy usually result in producing some energy in the form of heat, which leaks away by radiation or conduction (such as from engines, electrical wires, hot-water tanks, our bodies, and stereo systems). Further, when heat is conducted or radiated into a fluid, currents are set up that usually enhance the transfer of heat. Although materials that conduct or radiate heat very poorly can be used to reduce heat loss, it can never be prevented completely. Therefore the total amount of energy available for transformation is almost always decreasing. For example, almost all of the energy stored in the molecules of gasoline used during an automobile trip goes, by way of friction and exhaust, into producing a slightly warmer car, road, and air. But even if such diffused energy is prevented from leaking away, it tends to distribute itself evenly and thus may no longer be useful to us. This is because energy can accomplish transformations only when it is concentrated more in some places than in others (such as in falling water, in high-energy molecules in fuels and food, in unstable nuclei, and in radiation from the intensely hot sun). When energy is transformed into heat energy that diffuses all over, further transformations are less likely. The reason that heat tends always to diffuse from warmer places to cooler places is a matter of probability. Heat energy in a material consists of the disordered motions of its perpetually colliding atoms or molecules. As very large numbers of atoms or molecules in one region of a material repeatedly and randomly collide with those of a neighboring region, there are far more ways in which their energy of random motion can end up shared about equally throughout both regions than there are ways in which it can end up more concentrated in one region. The disordered sharing of heat energy all over is therefore far more likely to occur than any more orderly concentration of heat energy in any one place. More generally, in any interactions of atoms or molecules, the statistical odds are that they will end up in more disorder than they began with. It is, however, entirely possible for some systems to increase in orderliness—as long as systems connected to them increase even more in disorderliness. The cells of a human organism, for example, are always busy increasing order, as in building complex molecules and body structures. But this occurs at the cost of increasing the disorder around us even more—as in breaking down the molecular structure of food we eat and in warming up our surroundings. The point is that the total amount of disorder always tends to increase. Benchmarks for Science Literacy: Energy is a mysterious concept, even though its various forms can be precisely defined and measured. At the simplest level, children can think of energy as something needed to make things go, run, or happen. But they have difficulty distinguishing energy needs from other needs—plants need water to live and grow; cars need water, oil, and tires; people need sleep, etc. People in general are likely to think of energy as a substance, with flow and conservation analogous to that of matter. That is not correct, but for most people it can be an acceptable analogy. Although learning about energy does not make it much less mysterious, it is worth trying to understand because a wide variety of scientific explanations are difficult to follow without some knowledge of the concept of energy. Energy is a major exception to the principle that students should understand ideas before being given labels for them. Children benefit from talking about energy before they are able to define it. Ideas about energy that students encounter outside of school—for example, getting "quick energy" from a candy bar or turning off a light so as not to "waste energy"—may be imprecise but are reasonably consistent with ideas about energy that we want students to learn. Three energy-related ideas may be more important than the idea of energy itself. One is energy transformation. All physical events involve transferring energy or changing one form of energy into another—radiant to electrical, chemical to mechanical, and so on. A second idea is the conservation of energy. Whenever energy is reduced in one place, it is increased somewhere else by exactly the same amount. A third idea is that whenever there is a transformation of energy, some of it is likely to go into heat, which spreads around and is therefore not available for use. Heat energy itself is a surprisingly difficult idea for students, who thoroughly confound it with the idea of temperature. A great deal of work is required for students to make the distinction successfully, and the heat/temperature distinction may join mass/weight, speed/acceleration, and power/energy distinctions as topics that, for purposes of literacy, are not worth the extraordinary time required to learn them. Because dissipated heat energy is at a lower temperature, some students' confusion about heat and temperature leads them to infer that the amount of energy has been reduced. On the other hand, some students' idea that dissipated heat energy has been "exhausted" or "expended" may be tolerably close to the truth. Similarly, units and formulas for kinetic and potential energy are more difficult than they are worth for the semi-quantitative understanding that we seek here. But the notion of potential energy is still useful for some situations in which motion might occur (for example, gravitational energy in water behind a dam, mechanical energy in a cocked mousetrap, or chemical energy in a flashlight battery or sugar molecule). Work, in the specialized sense used in physics, is often considered a useful, even necessary, concept for dealing with ideas of energy. These benchmarks propose to do without a technical definition of work for purposes of basic literacy, because it is so greatly confused with the common English-language meaning of the word. The calculation of work as force times distance is not essential to understanding many important ideas about energy. Running makes you tired; rubbing your hands together makes them warmer; coming out of water makes you feel cool. Older students can grasp these ideas in a general way, but even they should not be expected to understand them deeply. For young students, it may be enough at first to convince them that energy is needed to get physical things to happen and that they should get in the habit of wondering where the energy came from. Then, as they study physical, chemical, and biological systems, many opportunities arise for them to see the many different forms energy takes and to find out how useful the energy concepts are. Teachers have to decide what constitutes a sufficient understanding of energy and its transformations and conservation. As the benchmarks below indicate, in harmony with Science for All Americans, qualitative approximations are more important and should have priority. Much time can be invested in having students memorize definitions-for heat, temperature, system, transformation, entropy, and the like—with little to show for it in the way of understanding. K- Grade 2: No effort to introduce energy as a scientific idea ought to be organized in these first years. If children use the term energy to indicate how much pep they have, that is perfectly all right, in that the meaning is clear and no technical mischief has been done. By the end of the 2nd grade, students should be familiar with a variety of ways of making things go and should consider "What makes it go?" to be an interesting question to ask. Once they learn that batteries wear down and cars run out of gasoline, turning off unneeded appliances can be said to "save on batteries" and "save on gas." The idea that is accessible at this age is that keeping anything going uses up some resource. (Little is gained by having children answer, "Energy.") By the end of the 2nd grade, students should know that The sun warms the land, air, and water. Grades 3-5 Investing much time and effort in developing formal energy concepts can wait. The importance of energy, after all, is that it is a useful idea. It helps make sense out of a very large number of things that go on in the physical and biological and engineering worlds. But until students have reached a certain point in their understanding of bits and pieces of the world, they gain little by having such a tool. It is a matter of timing. The one aspect of the energy story in which students of this age can make some headway is heat, which is produced almost everywhere. In their science and technology activities during these years, students should be alerted to look for things and processes that give off heat—lights, radios, television sets, the sun, sawing wood, polishing surfaces, bending things, running motors, people, animals, etc.—and then for those that seem not to give off heat. Also, the time is appropriate to explore how heat spreads from one place to another and what can be done to contain it or shield things from it. Students' ideas of heat have many wrinkles. In some situations, cold is thought to be transferred rather than heat. Some materials may be thought to be intrinsically warm (blankets) or cold (metals). Objects that keep things warm—such as a sweater or mittens—may be thought to be sources of heat. Only a continuing mix of experiment and discussion is likely to dispel these ideas. Students need not come out of this grade span understanding heat or its difference from temperature. In this spirit, there is little to be gained by having youngsters refer to heat as heat energy. More important, students should become familiar with the warming of objects that start out cooler than their environment, and vice versa. Computer labware probes and graphic displays that detect small changes in temperature and plot them can be used by students to examine many instances of heat exchange. Because many students think of cold as a substance that spreads like heat, there may be some advantage in translating descriptions of transfer of cold into terms of transfer of heat. By the end of the 5th grade, students should know that When two objects are rubbed against each other, they both get warmer. In addition, many mechanical and electrical devices get warmer when they are used. 4E/E1* When warmer things are put with cooler ones, the warmer things get cooler and the cooler things get warmer until they all are the same temperature. 4E/E2a* When warmer things are put with cooler ones, heat is transferred from the warmer ones to the cooler ones. 4E/E2b* A warmer object can warm a cooler one by contact or at a distance. 4E/E2c Grades 6 - 8 At this level, students should be introduced to energy primarily through energy transformations. Students should trace where energy comes from (and goes next) in examples that involve several different forms of energy along the way: heat, light, motion of objects, chemical, and elastically distorted materials. To change something's speed, to bend or stretch things, to heat or cool them, to push things together or tear them apart all require transfers (and some transformations) of energy. At this early stage, there may be some confusion in students' minds between energy and energy sources. Focusing on energy transformations may get around this somewhat. Food, gasoline, and batteries obviously get used up. But the energy they contain does not disappear; it is changed into other forms of energy. The most primitive idea is that the energy needed for an event must come from somewhere. That should trigger children's interest in asking, for any situation, where the energy comes from and (later) asking where it goes. Where it comes from is usually much more evident than where it goes, because some usually diffuses away as radiation and random molecular motion. A slightly more sophisticated proposition is the semiquantitative one that whenever some energy seems to show up in one place, some will be found to disappear from another. Eventually, the energy idea can become quantitative: If we can keep track of how much energy of each kind increases and decreases, we find that whenever the energy in one place decreases, the energy in other places increases by just the same amount. This energy-cannot-be-created-or-destroyed way of stating conservation fully may be more intuitive than the abstraction of a constant energy total within an isolated system. The quantitative (equal amounts) idea should probably wait until high school. Convection is not so much an independent means of heat transfer as it is an aid to transfer of heat by conduction and radiation. Convection currents appear spontaneously when density differences caused by heating (conduction and radiation) are acted on by a gravitational field. (Though not in space stations, unless they are rotating.) But these subtleties are not appropriate for most 8th graders. By the end of the 8th grade, students should know that Whenever energy appears in one place, it must have disappeared from another. Whenever energy is lost from somewhere, it must have gone somewhere else. Sometimes when energy appears to be lost, it actually has been transferred to a system that is so large that the effect of the transferred energy is imperceptible. 4E/M1* Energy can be transferred from one system to another (or from a system to its environment) in different ways: 1) thermally, when a warmer object is in contact with a cooler one; 2) mechanically, when two objects push or pull on each other over a distance; 3) electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device; or 4) by electromagnetic waves. 4E/M2* Thermal energy is transferred through a material by the collisions of atoms within the material. Over time, the thermal energy tends to spread out through a material and from one material to another if they are in contact. Thermal energy can also be transferred by means of currents in air, water, or other fluids. In addition, some thermal energy in all materials is transformed into light energy and radiated into the environment by electromagnetic waves; that light energy can be transformed back into thermal energy when the electromagnetic waves strike another material. As a result, a material tends to cool down unless some other form of energy is converted to thermal energy in the material. 4E/M3* Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves. 4E/M4* Light and other electromagnetic waves can warm objects. How much an object's temperature increases depends on how intense the light striking its surface is, how long the light shines on the object, and how much of the light is absorbed. 4E/M6** PLANNING RESOURCES Big Ideas: Energy transfers when it moves in the same form. Heat is a form of energy. Heat energy can be transferred. Heat energy is a property of many substances and many processes give off heat energy. Essential Questions: What is heat? How can heat change the properties of a substance? Does heat energy behave in predictable ways? How does heat move from one place to another? How do we explain conduction? How do we explain convection? How do we explain radiation? What are some natural examples of each type of heat transfer? How do matter and energy interact? What is temperature? Enduring Understandings: Heat energy is a property of many substances and many processes give off heat energy. Heat energy moves in predictable ways. When two objects are rubbed against each other, they both get warmer. In addition, many mechanical and electrical devices get warmer when they are used. When warmer things are put with cooler ones, the warmer things get cooler and the cooler things get warmer until they all are the same temperature. When warmer things are put with cooler ones, heat is transferred from the warmer ones to the cooler ones. A warmer object can warm a cooler one by contact or at a distance. Identify Misconceptions: Use formative probes: Uncovering Student ideas in Science, Volumes 1-4, by Page Keeley (I) Volume 1 The Mitten Problem p. 103 (II) Volume 1 Objects and temperature p. 109 (III) Volume 2 Turning the Dial p. 47 (IV) Volume 2 Boiling Time and Temperature p. 53 (V) Volume 2 Freezing Ice p. 59 (VI) Volume 2 Ice Cold lemonade p. 78 (VII) Volume 2 Mixing water p. 83 (VIII) Volume 3 Where did the water come from? P. 163 (IX) Volume 4 Iron Bar p. 17 (X) Volume 4 Ice Water p. 45 (XI) Volume 4 Warming Water p. 53 Formative Assessment Probes (articles, how-to, free-online) by Page Keeley, et al http://pal.lternet.edu/docs/outreach/educators/education_pedagogy_research/assessment_probes_unc overing_student_ideas.pdf http://www.ode.state.or.us/teachlearn/subjects/science/resources/msef2010 formative_assessment_probes.pdf Annotated TEACHING Resources: SciGirls Doghouse Design http://pbskids.org/dragonflytv/pdf/DoghouseDesign.pdf This activity (on page 2 of the PDF) is a full inquiry investigation into absorption and reflection of radiant energy. In order to build a house that keeps a dog as cool possible in the heat, learners set up an experiment to find out if paint color affects temperature. Atmospheric Processes--Radiation http://www.ucar.edu/learn/1_1_2_5t.htm This activity begins with an explanation of the heat transfer processes in general and then focuses on radiation. In the activity, students investigate how different surfaces absorb heat and apply their experience with the surfaces to interpret real-world situations. Atmospheric Processes-Conduction http://www.ucar.edu/learn/1_1_2_6t.htm This activity begins with an explanation of the heat transfer process of conduction, the process by which heat energy is transmitted through collisions between neighboring molecules. In the activity, students are asked to explain the process of conduction and that different materials conduct at different rates. Atmospheric processes – Convection http://www.ucar.edu/learn/1_1_2_7t.htm This activity begins with an explanation of the heat transfer process of convection. In the activity students observe convection in a liquid and in air. Build a Solar Oven http://www.re-energy.ca/solar-oven This website has lesson plans to build energy projects such as this solar oven. Teacher support and information is also available. The Sun Times: The Global Sun Temperature Project http://www.ciese.org/curriculum/tempproj/ This is the home page of a global project developed to involve K-12 students in a study of global climate and temperature. Participation is free with registration. Students measure daily temperature, record the number of minutes of sunlight per day, and submit their data online. The web site contains tools for data comparison and storage. Students graph and analyze results, and then share conclusions about causes of global temperature variation in a final report submitted to the website. Included are detailed project instructions, a teacher guide, reference material, and a student discussion forum. Cycles of the Earth and Atmosphere: Introduction to the Atmosphere http://www.ucar.edu/learn/1_1_1.htm This web page is a module for Grades 5-8 on the topic of Earth's atmosphere. It contains background information for teachers on atmospheric gases and their properties, explains how energy is transferred between the earth's surface and the atmosphere, and discusses the role ocean currents play in transferring heat. Included are links to seven classroom activities and labs on radiation, conduction, convection, the water cycle, and more. Teachers Domain HEAT TRANSFER http://www.teachersdomain.org/resource/lsps07.sci.phys.energy.heattransfer/ This item is an interactive Flash animation for Grades 5-8 on the topic of heat. Users explore methods of heat transfer and classify examples from everyday life. Three methods of heat transfer are depicted: conduction, convection, and radiation. Teach Engineering: How Hot Is It? http://www.teachengineering.org/view_lesson.php?url=http://www.teachengineering.org/collection/c ub_/lessons/cub_energy2/cub_energy2_lesson06.xml In this 3-day module for Grades 3-5, kids have fun learning about thermometers, temperature conversions, conduction, radiation, convection, and heat capacity. Well-organized resource includes a teacher-led introduction, a hands-on class activity, and an inquiry-based lab. Teach Engineering: Make Your Own Temperature Scale http://www.teachengineering.org/view_activity.php?url=http://www.teachengineering.com/collection/ cub_/activities/cub_energy2/cub_energy2_lesson06_activity1.xml In this 50-minute activity for grades 3-5, students construct a simple thermometer using 2-liter bottles, straws, and an alcohol-water mixture. The primary objective is to help young students understand the difference between temperature and thermal energy. How Much Heat Will It Hold? http://www.teachengineering.org/view_activity.php?url=http://www.teachengineering.org/collection/c ub_/activities/cub_energy2/cub_energy2_lesson06_activity2.xml This is a 50-minute lab for grades 3-5 on the topic of heat capacity. Students work in teams to collect data on the heat capacity of various common materials. The main objective is to promote understanding of how heat capacity is related to the storage of thermal energy. NEOK12 Heat and Temperature http://www.neok12.com/Heat-Temperature.htm A collection of videos, lessons and games. Energy: Heat: Conduction, Convection, and Radiation http://ethemes.missouri.edu/themes/1369 Explore these sites to learn about heat transfer and thermal insulators. Find out how molecules movement in all types of matter generates heat. Learn about conduction, convection, and radiation. *NASA Resource: Hurricanes as Heat Engines http://nasawavelength.org/resource/nw-000-000-002-201/ Students examine authentic sea surface temperature data to investigate how hurricanes extract heat energy from the ocean surface. Video Resources: Teachers Domain http://www.teachersdomain.org/ Free digital media for educational use. Bill Nye http://www.teachertube.com/viewVideo.php?video_id=186099 Heat video 1 What heat is http://www.teachertube.com/viewVideo.php?video_id=186395&title=Bill_Nye_heat_2 Heat video 2 transfer of heat http://www.videosurf.com/video/bill-nye-the-science-guy-on-heat-full-clip-86007993 Heat video full clip HEAT Rap Video http://www.teachertube.com/viewVideo.php?video_id=159713 Text Resources: http://www.eschooltoday.com/energy/kinds-of-energy/what-is-thermal-energy.html http://www.physics4kids.com/files/thermo_transfer.html http://www.explainthatstuff.com/heat.html http://www.bbc.co.uk/bitesize/ks2/science/materials/heat/read/1/ http://www.srh.noaa.gov/jetstream/atmos/heat.htm https://www.ck12.org/physics/Heat-Temperature-and-Thermal-Energy-Transfer/ Terminology: conduction convection radiation temperature Writing Prompts: 1. Write an essay describing what happens to the heat energy from a gas stove when you boil an egg in a pot of water. 2. It is freezing outside! Describe how you will dress in order to stay warm as you hike to the park a half mile away. 3. You have just made yourself a nice hot cup of tea. You are blowing on the top of the tea so you will not burn your mouth. Write an essay explaining why the blowing will cool off the tea so that it is safe to drink. 4. There is a need to conserve energy; if we are to make our natural resources last as long as possible. Some people do this by lowering their thermostat in the winter months, and their homes feel a little cool inside. Often, they have to wear sweaters indoors to stay warm. Do you think people should be required to conserve heat energy this way? Explain your position. 5. In North Carolina, we experience four seasons. This doesn’t happen everywhere on earth. Some places stay hot year round, while others stay cold year round. If you had to relocate to such a place, and you had to choose between them, which would you choose – hot or cold? Explain the reasons for your choice.