Heat+transfer

=Heat Transfer= toc

Essential Question
What Will We Do? Students doing the **Chocolate Melt** decide on a container-tin can, cardboard box, plastic bucket, paper bag, or similar object-to use as a solar cooker. Then they consider how to melt a refrigerated standard-size milk chocolate chip that has been placed on the end of a toothpick inside the cooker in as short a time as possible. This includes figuring out how to reshape the container so that the heat from the sun is concentrated on the chocolate chip, deciding what colors and textures to use for lining inside surfaces and insulating the cooker, examining where to put the chocolate chip, and identifying how to point the cooker at the sun. Reviewing scientific information helps students improve the effectiveness of their cooker designs and make predictions about the ones they think will cook the most rapidly. On **Chocolate Melting Day**, students collect and record data to share with other students doing the challenge.

Content Knowledge

 * ~ GA: Science (GPS) GA: Grade 8 Habits of the Mind ||
 * S8CS1. Students will explore the importance of curiosity, honesty, openness, and skepticism in science and will exhibit these traits in their own efforts to understand how the world works. ||
 * a. Understand the importance of-and keep-honest, clear, and accurate records in science. ||  ||
 * b. Understand that hypotheses can be valuable even if they turn out not to be completely accurate. ||  ||
 * S8CS2. Students will use standard safety practices for all classroom laboratory and field investigations. ||
 * a. Follow correct procedures for use of scientific apparatus. ||  ||
 * b. Demonstrate appropriate techniques in all laboratory situations. ||  ||
 * c. Follow correct protocol for identifying and reporting safety problems and violations. ||  ||
 * S8CS3. Students will have the computation and estimation skills necessary for analyzing data and following scientific explanations. ||
 * a. Analyze scientific data by using, interpreting, and comparing numbers in several equivalent forms, such as integers, fractions, decimals, and percents. ||  ||
 * b. Find the mean, median, and mode and use them to analyze a set of scientific data. ||  ||
 * c. Apply the metric system to scientific investigations that include metric to metric conversions (i.e., centimeters to meters). ||  ||
 * d. Decide what degree of precision is adequate, and round off appropriately. ||  ||
 * e. Address the relationship between accuracy and precision. ||  ||
 * f. Use ratios and proportions, including constant rates, in appropriate problems. ||  ||
 * S8CS4. Students will use tools and instruments for observing, measuring, and manipulating equipment and materials in scientific activities utilizing safe laboratory procedures. ||
 * a. Use appropriate technology to store and retrieve scientific information in topical, alphabetical, numerical, and keyword files, and create simple files. ||  ||
 * b. Use appropriate tools and units for measuring objects and/or substances. ||  ||
 * c. Learn and use standard safety practices when conducting scientific investigations. ||  ||
 * S8CS5. Students will use the ideas of system, model, change, and scale in exploring scientific and technological matters. ||
 * a. Observe and explain how parts can be related to other parts in a system such as the role of simple machines in complex machines. ||  ||
 * b. Understand that different models (such as physical replicas, pictures, and analogies) can be used to represent the same thing. ||  ||
 * S8CS6. Students will communicate scientific ideas and activities clearly. ||
 * a. Write clear, step-by-step instructions for conducting scientific investigations, operating a piece of equipment, or following a procedure. ||  ||
 * b. Write for scientific purposes incorporating information from a circle, bar, or line graph, data tables, diagrams, and symbols. ||  ||
 * c. Organize scientific information in appropriate tables, charts, and graphs, and identify relationships they reveal. ||  ||
 * S8CS7. Students will question scientific claims and arguments effectively. ||
 * c. Question the value of arguments based on small samples of data, biased samples, or samples for which there was no control. ||  ||
 * d. Recognize that there may be more than one way to interpret a given set of findings. ||  ||
 * ~ GA: Science (GPS) GA: Grade 8 Nature of Science ||
 * S8CS8. Students will be familiar with the characteristics of scientific knowledge and how it is achieved. ||
 * a. When similar investigations give different results, the scientific challenge is to judge whether the differences are trivial or significant, which often requires further study. Even with similar results, scientists may wait until an investigation has been repeated many times before accepting the results as meaningful. ||  ||
 * b. When new experimental results are inconsistent with an existing, well-established theory, scientists may pursue further experimentation to determine whether the results are flawed or the theory requires modification. ||  ||
 * c. As prevailing theories are challenged by new information, scientific knowledge may change. ||  ||
 * S8CS9. Students will understand the features of the process of scientific inquiry. ||
 * a. Investigations are conducted for different reasons, which include exploring new phenomena, confirming previous results, testing how well a theory predicts, and comparing different theories. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. ||  ||
 * b. Scientific investigations usually involve collecting evidence, reasoning, devising hypotheses, and formulating explanations to make sense of collected evidence. ||  ||
 * c. Scientific experiments investigate the effect of one variable on another. All other variables are kept constant. ||  ||
 * d. Scientists often collaborate to design research. To prevent this bias, scientists conduct independent studies of the same questions. ||  ||
 * e. Accurate record keeping, data sharing, and replication of results are essential for maintaining an investigator's credibility with other scientists and society. ||  ||
 * f. Scientists use technology and mathematics to enhance the process of scientific inquiry. ||  ||
 * ~ GA: Science (GPS) GA: Grade 8 Reading Across Curriculum ||
 * S8CS10. Students will enhance reading in all curriculum areas by: a. Reading in All Curriculum Areas ||
 * Read both informational and fictional texts in a variety of genres and modes of discourse. ||  ||
 * Read technical texts related to various subject areas. ||  ||
 * b. Discussing books ||
 * Respond to a variety of texts in multiple modes of discourse. ||  ||
 * Relate messages and themes from one subject area to messages and themes in another area. ||  ||
 * Examine author's purpose in writing. ||  ||
 * Recognize the features of disciplinary texts. ||  ||
 * c. Building vocabulary knowledge ||
 * Demonstrate an understanding of contextual vocabulary in various subjects. ||  ||
 * Use content vocabulary in writing and speaking. ||  ||
 * Explore understanding of new words found in subject area texts. ||  ||
 * d. Establishing context ||
 * Explore life experiences related to subject area content. ||  ||
 * Discuss in both writing and speaking how certain words are subject area related. ||  ||
 * Determine strategies for finding content and contextual meaning for unknown words. ||  ||
 * ~ GA: Science (GPS) GA: Grade 8 Physical Science ||
 * S8P1. Students will examine the scientific view of the nature of matter. ||
 * a. Distinguish between atoms and molecules. ||  ||
 * b. Describe the difference between pure substances (elements and compounds) and mixtures. ||  ||
 * c. Describe the movement of particles in solids, liquids, gases, and plasmas states. ||  ||
 * d. Distinguish between physical and chemical properties of matter as physical (i.e., density, melting point, boiling point) or chemical (i.e., reactivity, combustibility). ||  ||
 * e. Distinguish between changes in matter as physical (i.e., physical change) or chemical (development of a gas, formation of precipitate, and change in color). ||  ||
 * g. Identify and demonstrate the Law of Conservation of Matter. ||  ||
 * S8P2. Students will be familiar with the forms and transformations of energy. ||
 * a. Explain energy transformation in terms of the Law of Conservation of Energy. ||  ||
 * c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics. ||  ||
 * d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection). ||

Content Standards: 5-8
 * **Science as Inquiry, A, Abilities Necessary to Do Scientific Inquiry**, "Identify Questions…Design and Conduct an Investigation…Use Appropriate Techniques…Use Evidence …Make Relationships…Recognize Alternatives … Communicate…Use Mathematics…"(pages 145-6).
 * **Science as Inquiry, A, Understandings About Scientific Inquiry**, "Mathematics is important in all aspects of scientific inquiry…Technology used to gather data enhances accuracy and allows scientists to analyze and quantify results of investigations." (page 148).
 * **Physical Science, B, Transfer of Energy**, "Energy is a property of many substances and is associated with heat, light…Heat move in predictable ways, flowing from warmer objects to cooler ones, until both reach the same temperature…Light interacts with matter by…scattering…The sun is a major source of energy for changes on the earth's surface. The sun loses energy by emitting light. A tiny fraction of that light reaches the earth, transferring energy from the sun to the earth." (page 155).
 * **Earth and Space Science, D, Earth in the Solar System**, "The sun is the major source of energy for phenomena on the earth's surface…" (page 161).
 * **Science and Technology, E, Abilities of Technological Design**, "Identify a Problem…Propose a Solution…Implement Proposed Solutions…Evaluate a Product or Design." (page 165).

Vocabulary
insulator, conductor, phase change, convection, radiation, conduction, thermal, reflection

Background knowledge
[|SciLinks- Energy Transfer activities]





Designing Your Cooker
 * Find a container. You might use a shoebox, plastic bucket or jar, paper bag, milk carton, yogurt tub, or cereal box. **Avoid anything made of glass!**
 * Look carefully at some of these solar oven designs and try to figure out what makes them cook food quickly. Remember you want to concentrate sunlight on a chocolate chip that is placed on the end of a toothpick.
 * Think about what you've learned from studying solar ovens. Also, find out [|how your solar cooker works]. Then use the questions below to help you design your solar cooker:
 * What material will you use to let sunlight shine into your cooker? Remember all of the sun's rays needs to shine through the material?
 * What can you use to line the inside surfaces of the cooker? Remember you want to concentrate as much sunlight on the chocolate chip as possible.
 * What can you do to hold the heat inside the cooker? Remember cold air can enter the cooker through holes and warm air can escape through outside surfaces.
 * How will you point your cooker to catch the sun's rays? Remember you want the chocolate chip to melt as quickly as possible.
 * How will you hold the toothpick and chocolate chip in place? Remember you want to concentrate sunlight on the chocolate chip so that it melts as quickly as possible.

Evidence of knowledge
**1. Students will contribute to either class/team wiki and/or GoogleDocs.** **2. Student will participate in labs, providing summaries as to how these labs helped to create their design.** **3. Students will create** **and present** **documentation on the process and their findings.** **4. Students will participate and gather data on Chocolate Melting Day** >> >>
 * 1) Carry your solar cooker, data recording sheet, timer, thermometer for measuring the air temperature outside of the cooker, refrigerated chocolate chip, and anything else you might need to a shady location.
 * 2) Record the following information: season of the year, time of day, color and shininess of the inside surfaces of your cooker, and sky conditions on the data - recording sheet.
 * 3) Set up your cooker, carry it to the test spot, and record the time you started melting the chocolate chip. Place a thermometer next to your cooker. (Be sure the sun is not shining on the bulb of the thermometer.)
 * 4) <span style="background-color: #ffffff; font-family: Times; font-family: Verdana,Geneva,Arial,Helvetica,sans-serif; font-size: 12px; font-size: medium;">Record the time you stopped melting the chocolate chip and the temperature of the air outside of the cooker on the data recording sheet.
 * 5) <span style="background-color: #ffffff; font-family: Times; font-family: Verdana,Geneva,Arial,Helvetica,sans-serif; font-size: 12px; font-size: medium;">Test to see the chocolate is completely melted by squishing the chip between thumb and forefinger. If it has melted completely, go to Step 6. If it has not melted completely, go to Step 7.
 * 6) <span style="background-color: #ffffff; font-family: Times; font-family: Verdana,Geneva,Arial,Helvetica,sans-serif; font-size: 12px; font-size: medium;">Calculate the time it took to melt the chocolate chip (time you stopped melting minus the time you started). Record the number of minutes, and seconds on your data-recording sheet.
 * 7) <span style="background-color: #ffffff; font-family: Times; font-family: Verdana,Geneva,Arial,Helvetica,sans-serif; font-size: 12px; font-size: medium;">Take your cooker to the shade and, when it is your turn, repeat Steps 3-5 as often as required.
 * 8) <span style="background-color: #ffffff; font-family: Verdana,Geneva,Arial,Helvetica,sans-serif; font-size: medium;">Clean everything up before returning to the classroom and sending your data to the**Chocolate Melt**database.

Links
[|solar cooker option]

[|solar idea]

The concept, plan, and content are all from [|Online Science-athon]