Summary

In this lesson, students will learn about the use of alternative cooking fuels that could replace burning wood, coal, or other smoke-producing materials to heat and cook food in developing nations, focusing on solar cookers. They will watch a video and read an article that provide a general overview of the need for alternative fuels. Then, in small groups, students will research, design, build, and test a solar cooker to determine if it is an effective method of cooking food in a developing nation. They will give a presentation to the class on their design, test results, and any improvements they would make to their initial design, and they will answer some reflection questions about the solar cookers made by their class and their role in the group project.

Grade Level

Middle School and High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• MS-PS3-3: Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
• MS-ETS1-2: Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
• MS-ETS1-3: Analyze data from tests to determine similarities and difference among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
• MS-ETS1-4: Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be reached.
• HS-ETS1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
• HS-ETS1-2: Design a solution to a complex real-world problem by breaking it down into small, more manageable problems that can be solved through engineering.
• HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Analyzing and Interpreting Data
  • Constructing Explanations and Designing Solutions
  • Engaging in Argument from Evidence
  • Obtaining, Evaluating, and Communicating Information

Objectives

By the end of this lesson, students should be able to:

• Explain how using alternative fuels could benefit human health and the environment.
• Research, design, and build a solar cooker.
• Collect and analyze data to determine whether a solar cooker could be an effective method of cooking in a developing nation.
• Suggest adjustments to their solar cooker design that could make it more useful/effective.

Chemistry Topics

This lesson supports students’ understanding of:

• Renewable energy
• Heat transfer
• Specific heat

Time

Teacher Preparation: minimal (< 15 minutes) except purchasing of supplies if you want to provide them to your students
Lesson: 300-480 minutes (5-8 hours) total class time (over the course of 5-10 class periods)

• Note that several parts of this lesson can be completed as homework to cut down on class time needed. (See notes below and in the Teacher Notes section.)
• Part 1: Introduction and Research
  • Watch video, read article, complete “Alternative Cooking Fuels” worksheet: 30-45 minutes (all or part of worksheet could be assigned as homework)
  • Complete “Solar Cooker Design Research” worksheet and select design: 30-45 minutes
• Part 2: Solar Cooker Construction
  • Build solar cookers: 60-120 minutes
  • Complete “Solar Cooker Cost Analysis” worksheet: 20-30 minutes (could be assigned as homework)
• Part 3: Solar Cooker Testing
  • Set up lab and collect data: 50-60 minutes
  • Complete graph and analysis questions: 30-45 minutes (could be assigned as homework)
• Part 4: Presentation and Reflection
  • Prepare presentation: 30-60 minutes (could be assigned as homework)
  • Give presentations to the class: 60-90 minutes (could be shortened by replacing this with self-guided “walking tour” or gallery walk of other groups’ presentations)

Materials

Part 1: Introduction and Research

• Student worksheets “Alternative Cooking Fuels” and “Solar Cooker Design Research”
• Computer with internet access and projector with sound for watching Switch On: Modern Cooking Fuels video
• Print or digital access to the article 'Whole forests will be saved': Is solar cooking more than just a flash in the pan?
• Internet access and computer/tablet to research solar cooker types

Part 2: Solar Cooker Construction

• Student worksheet “Solar Cooker Cost Analysis”
• Supplies for solar cookers (this will depend on what the groups choose to make, but these are some of the most frequently used items)
  • Foil
  • Thick plastic wrap
  • Tape
  • Scissors (or box cutter)
  • Rulers
  • Black or other dark construction paper
  • Cardboard (pizza box, shoe box, delivery box, etc.)

Part 3: Solar Cooker Testing

• Student worksheet “Solar Cooker Testing”
• Student-built solar cookers
• Digital or glass thermometers (2 per group)
• Graduated cylinder (1 per group)
• Test tube with cork or rubber stopper with a hole for the thermometer (1 per group)
• Hot-hands or heat-resistant gloves for handling hot equipment in the solar cookers
• Heat lamps (optional, if there is no sun these are a good alternative)

Part 4: Presentation and Reflection

• Student worksheet “Post-Project Reflection”
• Presentation rubric
• Computers to make digital presentations, or poster boards, markers, construction paper, glue, etc. for poster presentations

Safety

• Do not consume lab solutions, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.
• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Students should be cautious when using sharp instruments to cut cardboard and always point sharp objects away from themselves and others.

Teacher Notes

• This lesson was developed as part of the AACT Chemistry and Sustainability content writing team. It connects with the following UN Sustainable Development Goals:
  • Goal 3: Good Health and Well-Being – Ensure healthy lives and promote well-being for all at all ages.
  • Goal 7: Affordable and Clean Energy – Ensure access to affordable, reliable, sustainable, and modern energy for all.
• Prior to starting this lesson, students should be familiar with the concepts of heat energy, specific heat, temperature, and constructing a graph.
• This lesson will give students an opportunity to develop a wide range of scientific and engineering skills as they design, build, test, and suggest improvements for a solar cooker that could be used as a cleaner, healthier, inexpensive cooking tool in developing nations.

Part 1: Introduction and Research

• Students will watch “Switch On: Modern Cooking Fuels” and answer questions 1–7 on the “Alternative Cooking Fuels” worksheet. This video details how some groups are trying to switch families to cleaner cooking fuels instead of using wood, which can cause damage to lungs and costs a significant amount of money.
• Students will also read the article “'Whole forests will be saved': Is solar cooking more than just a flash in the pan?” and answer the remaining questions on the handout.
  • If class time is limited, the video and/or article could be assigned to students as homework, or the video could be ended at 20 mins, which would skip the last 10 minutes covering electricity as an alternative to wood fuel sources. Students would still be able to complete all questions on the handout.
• Students will then get into groups of 2–3 and research three possible solar cooker designs they could build. (You may assign the groups or allow students to choose their own groups. There is a reflection worksheet that can be used at the end of the lesson that will allow students to describe how they contributed to the final product.)
  • Older students can probably have free range to choose any solar cooker design.
  • You may want to limit younger students to specific solar cooker designs (particularly, avoiding designs that require the use of boxcutters or other sharp cutting instruments beyond scissors).
  • This website provides six different designs that are easy to build and low cost. Each solar cooker example links to detailed directions. These designs are easy for younger students to complete.
• Students will use the “Solar Cooker Design Research” handout to evaluate their three potential solar cooker designs, the pros and cons of each design, and all the items needed to build each solar cooker. They will use their research to decide which design they will build and indicate their choice on a sign-up sheet or Google Doc. This allows you to briefly look over student plans before building begins to ensure all groups have chosen a design and know what materials they will need.
• Depending on your student population, you may want to have them bring any supplies they need, or you may want to provide some or all of the supplies, particularly if it would be a hardship for your students and their families to have to purchase these. Most of the solar cooker designs have supply lists that should be well under $10. If opting to have students bring their own supplies, you could have them do this research on a Friday to provide them with the weekend to obtain any materials they need.
  • If students are bringing their own supplies, not every student needs to bring in a roll of aluminum foil or plastic wrap, for example. You could have students sign up for which common supplies they would like to bring in so that there will be enough of each material to go around.

Part 2: Solar Cooker Construction

• Students will build their solar cookers. Most will take no more than 2 hours to build. If time allows, they may also decorate their cooker if they choose to.
  • Before they start building their designs, make sure students are prepared to keep track of the amount of materials they use and the number of minutes it takes them to build their solar cooker, as this is part of the cost analysis section.
• Students will calculate the cost of the supplies and labor to build their solar cooker using the “Solar Cooker Cost Analysis” worksheet. You may want to adjust prices depending on the area you live in or the type of materials you use.
  • The cost of many of the items are measured in dollars per square foot, so students will need to calculate the square footage of the materials they use. You may want to review the formula for calculating area with students (area = length x width) before they start constructing their solar cookers.
  • The minimum hourly wage in Nepal provided on the worksheet is 77 rupees per hour, or $0.59 per hour, at the time of publication of this resource. You may wish to verify this is still fairly accurate before giving it to students, or you could have them use the minimum wage in your state instead.
  • If time is limited, students can record their materials and time during class and do the actual calculations and the questions at the end of the worksheet for homework.
• You can move on to the testing of the solar cookers or have students begin creating their presentation if they take less time to construct their solar cookers.

Part 3: Solar Cooker Testing

• Students will test their solar cookers using the procedures outlined in the “Solar Cooker Testing” worksheet. The best results will be obtained from a sunny and hot day. However, you can also do this with heat lamps. You could use heat lamps with 250 watt, 120-volt, incandescent bulbs. Using only one heat lamp per solar cooker produces poor data – using multiple heat lamps per solar cooker works much better.
• If time is limited, provide the worksheet to students in advance so they can familiarize themselves with the procedures and questions before they come to class on testing day. This should enable them to move more efficiently through the procedures in class.
• The students are asked to create a graph of their data, draw a line of best fit, and extrapolate how long it would take for their solar cooker to reach 350°F. If students need a refresher on how to create a good graph, they could review the Graphing Simulation. You could also allow them to use a graphing program, such as Excel or Google Sheets, to create a graph if you wish.
• Question 9 has students calculate the amount of heat energy absorbed by the water in their solar cooker using the equation q=mcΔT. If you have not yet covered quantitative calculations involving specific heat, you can use this as an opportunity to introduce the topic or remove this question before distributing it to students.
• Questions 10 and 11 ask students to think critically about the results of their tests and how they might improve their designs for real-world applications. Emphasize that this is the core of this lesson (and where many NGSS skills are developed), so students should put significant thought and time into their answers to these questions. They will also be useful to reference as students prepare their presentations.
• These solar cookers, even though they are homemade, can get hot! Encourage students to use caution when near their solar cookers and when handling any potentially hot equipment.

Part 4: Presentation and Reflection

• Students will create a presentation about their solar cooker and decide if it is an effective method of cooking for a developing nation. If time allows, students give their presentation to the class and/or turn it in for a final grade. Presentations can also be recorded outside of class time.
  • You could have students make a digital presentation (using something like PowerPoint or Prezi), or they could use poster board and markers, construction paper, etc. Students could be provided with either option, or you could select one.
  • If you do not have time for every group to present, you could have students set up their presentations throughout the classroom and walk around to view other groups’ projects, or even do a slightly more formalized “I like, I wonder, Next steps”-style gallery walk where students have a place to leave comments and questions for other groups.
• You may give students the “Presentation Rubric” handout, available for download in the sidebar, to guide them as they develop their presentation.
• If desired, students can also complete the “Post-Project Reflection” worksheet, which gives students an opportunity to comment on their classmates' projects and reflect on their contributions to their group. You could also give this worksheet at the beginning of this lesson so students can think about their role in their group from the start.

Extension options

• Have students implement some of their ideas for how to improve their solar cooker and run another trial with their “solar cooker 2.0” to see if their ideas produced better test results.
• Discuss additional related thermodynamics topics, such as heat transfer, phase changes, different temperature scales, and/or insulators and conductors.
  • Students could alter the design of their solar cooker to add more insulators or conductors to try to make it more efficient.
  • Students could do multiple trials in which they vary the amount of water used in the solar cooker and/or the size/shape of the container it’s in and measure the rate of heating.
• Have a prize for the group whose solar cooker reaches the highest temperature in 45 minutes.
• Create a cultural fair where students would present their solar cooker and information about a specific developing nation that would benefit from this type of cooking method.
• Provide a commercial solar cooker (many $50-$100 versions can be purchased online and reused each year) and compare students’ designs to the purchased one.