Students learn about using renewable energy from the Sun for heating and cooking as they build and compare the performance of four solar cooker designs. They explore the concepts of insulation, reflection, absorption, conduction and convection.
Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.
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- Colorado: Math
- Colorado: Science
- Common Core State Standards for Mathematics: Math
- 2. Represent real world and mathematical problems by graphing points in the first quadrant of the coordinate plane, and interpret coordinate values of points in the context of the situation. (Grade 5)  ...show
- International Technology and Engineering Educators Association: Technology
- Next Generation Science Standards: Science
- Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. (Grades 3 - 5)  ...show
- Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem. (Grades 3 - 5)  ...show
- Apply scientific ideas to design, test, and refine a device that converts energy from one form to another. (Grade 4)  ...show
- Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer. (Grades 6 - 8)  ...show
- Describe how engineers help develop solar cooking technology to benefit people in developing countries
- Describe the important properties of a solar cooker and their purposes.
- Describe the transformation of energy that takes place in a solar cooker.
- 250 ml beaker (or large glass jar) to hold 200 ml water
- A non-mercury thermometer
- Water (200 ml per cooker)
- Sunglasses (optional)
- Solar Cooker Worksheet, one per student
- Mini-size marshmallows (optional)
- Thin Hershey-brand chocolate bar (optional)
- Graham cracker (optional)
- 250 ml beaker (or large glass jar) to hold 200 ml water
- A non-mercury thermometer
- Water (200 ml)
- 1 cardboard box, ~12 in (30 cm) on the longest side (ask students to bring boxes from home)
- Rubber cement (or tape)
- Aluminum foil, roll or sheets, to line the inside of the box
- 1 cardboard box, ~12 in (30 cm) on the longest side (ask students to bring from home)
- Black paint and brushes (or black construction paper, scissors and glue)
- 1 cardboard box in which to prop the cone formed from the poster board (ask students to bring from home)
- 1 poster board, 35 in 35 in (90 cm 90 cm)
- Aluminum foil, to cover the poster board
- Rubber cement (or tape)
- 3 brass brads (or heavy-duty stapler)
- Pencil (to poke holes in the poster board if securing with brass brads)
- 1 rectangular cardboard box to make the frame, the longest side must be ~12 in (30 cm) (ask students to bring from home)
- 1 cardboard box to make the ends of the trough, the shortest side must be at least 9 in (23 cm) (ask students to bring boxes from home)
- 1 poster board, 11 in 14 in (28 cm 35 cm)
- Aluminum foil, to cover the poster board and trough ends
- Pencil (to poke holes in the cardboard)
- Rubber cement (or tape)
- Clear or masking tape
- 2 nuts
- 2 bolts
- Parabolic Solar Cooker Pattern
- 1 unpainted wire coat hanger (optional)
- Conduction = by direct contact of two materials
- Convection = by the interaction of fluid molecules (such as air or water)
- Radiation = by the movement of heat waves.
|Absorb:||To be taken into a material without transmission or reflection.|
|Conduction:||The transfer of heat from a region of higher temperature to a region of lower temperature by increased kinetic energy moving from molecule to molecule.|
|Convection:||Transfer of heat in a fluid (liquid or gas) when higher-temperature fluid expands and moves, creating heat transfer.|
|Deforestation:||To cut down and clear away the trees or forests.|
|Electromagnetic spectrum:||The entire range of wavelengths or frequencies of electromagnetic radiation extending from gamma rays to the longest radio waves and including visible light. In order of decreasing frequency: cosmic-ray photons, gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.|
|Erosion:||The process of destruction of a surface by abrasive action (for example, the soil eroded away after the trees were removed).|
|Fossil fuel:||A hydrocarbon deposit derived from living matter of a previous geologic time and used for fuel, such as coal, petroleum oil or natural gas.|
|Global warming:||An increase in the average temperature of the Earth's atmosphere, especially causing climatic change.|
|Greenhouse gases:||The atmospheric gases that contribute to the greenhouse effect by absorbing infrared radiation.|
|Habitat:||The area or environment where a person or ecological community lives.|
|Insulation:||A non-conductive material or substance used to prevent the transfer of heat, electricity or sound.|
|Parabolic:||A specific type of curved shape used in solar trough collectors. The shape focuses the sun at 30 to 100 times its normal intensity, achieving temperatures of more than 400 °C. Having the form of a parabola — a plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the curve.|
|Purify:||To rid of impurities; cleanse.|
|Radiation:||The emission and propagation of energy in the form of electromagnetic waves or particles (photons).|
|Reflect:||To cause to bend back or return upon striking a surface.|
|Thermal energy:||The energy an object has due to the motion of its particles.|
|Thermal mass:||Material used to store thermal energy (heat). Stone, concrete, adobe, brick and water work best. Thermal mass is used in a building to absorb or emit heat, and reduce interior temperature swings.|
|Transmit:||To allow to pass through a material.|
Before the Activity
- Divide the class into teams of three students each. Have student teams choose (or assign) the cooker type they want to make. The Box Panel Cooker and the Modified Box Panel Cooker are the easiest to construct.
- Collect boxes for the solar cookers. Ask students to bring empty boxes from home.
- Paint the inside of boxes for Cooker #2 the day before, so the paint has time to dry.
- Gather the rest of the materials and make copies of the Solar Cooker Worksheet.
- If making the parabolic solar cooker, make copies of the Parabolic Solar Cooker Pattern (one pattern per team, also see Figure 5) for the ends of the cooker.
- Organize the materials for each type of solar cooker at team workstations.
Day 1 — Building the Solar Cookers
- Cut off the top flaps of the box. (Or, remove the cover, if a shoe box.)
- Cut the cardboard box edges as shown in Figure 1, so the box opens up to lay flat, as indicated in Figure 2.
- To make the shiny inside surface of the box panel solar cooker, cut pieces of aluminum foil so they completely cover one side of the flattened cardboard box. Glue (or tape) the foil to the cardboard surface.
- Fold the flattened cardboard into a box shape again (see Figure 3) with the foil surface on the inside of the box, being careful not to rip the foil. The side and front walls are adjustable to help direct sunlight into the cooking area.
- Follow the directions for Cooker #1, the box panel cooker, but instead of lining the box with aluminum foil, paint the inside of the box with black paint (or line it with black construction paper).
- Ask students what advantages there might be to having the inside of the oven black. Why not use red or white or yellow paint (or paper)? What happens when you wear a black t-shirt on a sunny day compared to a white t-shirt? (Answer: Darker colors absorb heat better than light colors. So when you wear a black t-shirt in the sun you get hotter than if you wear a white t-shirt. Since we want our oven to get hot, we want to collect as much heat as possible. If we were to make our oven insides white, the heat would be reflected rather than absorbed and our oven would not get as hot.)
- Cut aluminum foil to fit the poster board. Glue (or tape) the foil to the poster board.
- As shown in Figure 4, roll the poster board into a cone with the foil surface on the inside, being careful not to damage the foil.
- Punch holes through the poster board where it overlaps at the bottom of the cone. Fasten the brass brads through these holes. Or, fasten securely using a strong stapler instead of the brads.
- Open up the box by cutting off or folding in the top flap(s), or removing the lid.
- Place stones or other weights in the box so it does not move in the wind. Place the solar cone cooker in the box, with its narrow side down.
- Referring to the Parabolic Solar Cooker Pattern (see Figure 5), cut the ends of the parabolic trough from the smaller cardboard box. Mark on the pieces of cardboard the locations for the holes. Use a pencil to make the holes on each piece of cardboard.
- Glue (or tape) aluminum foil to the poster board.
- Gently curve the poster board with the foil surface to the inside, and use tape to secure the trough-shaped poster board to the two, curved cardboard ends (see Figure 6).
- Cut the top flaps off the rectangular box. Cut a rectangle from one long side of the box (~4.5 in 12 in [11.4 cm 30.5 cm], as shown in Figure 6.
- Hold the trough in the frame so the hole to attach to the frame is at the corner of the box (see Figure 6). Mark the hole on both sides.
- Use a pencil to make the holes in the cardboard frame. Use the nuts and bolts to attach the parabolic trough to the box frame. Make sure the trough is stable, but can rotate easily.
- (Optional) To cook food, straighten the wire coat hanger and bend one end to make a handle. Push the wire through the hole on one side of the trough and out the hole on the other side.
- Take the cookers, thermometers, beakers, water and a timer outside. Remind students to put on their sunglasses. Position each cooker to receive maximum sunlight. Have the students pay careful attention to how they position their cooker so it receives the most sunlight and does not cast shadows inside the cooker. The side and front walls of the box cooker may be adjusted to better reflect sunlight onto the cooking area. Sometimes it helps to tilt or angle the cooker.
- Pour 200 ml of water into a beaker (or jar) for each cooker you are testing. As a control, place one container of 200 ml of water in the shade, with its own thermometer.
- Have teams place their beakers (or jars) in their cookers.
- Start the timer and have students measure the temperature of the water in their cookers every 2 minutes for 20 minutes, recording the temperature on their worksheets. Assign one student to measure and record the temperature of the control (shade) water jar at the same time intervals.
- Conclude with a class discussion, comparing results and graphs. How did each team's cooker temperature graph compare to the control (shade) temperature graph? Which solar cookers worked the best? How do you know? Did you adjust your cooker in any way to make it work better? What solar cooker characteristics made them work the best? Was there a certain location in each cooker that seemed to get the hottest? Ask students the post-activity discussion questions in the Assessment section.
- (Optional) Time to cook! Place a few mini marshmallows and a piece of thin chocolate on a graham cracker and place it in the oven to melt. (Note: See more snack suggestions in the Activity Extensions section.)
- Remind students to be cautious when poking holes and cutting cardboard or poster board.
- Wear sunglasses while outside since the reflection from aluminum foil is very bright.
- Where does the Earth get its energy? (Discussion points: Nearly all the energy comes from the Sun. Everything you eat originally got its energy from the Sun. Plants convert the Sun's energy into energy and animals get their energy from eating plants.)
- Can you name devices that get their energy from the Sun? (Possible answers: Cars, trucks, trains, boats and airplanes, computers, ovens, lights, televisions, alarm clocks; anything that uses electricity directly or indirectly got its energy from the Sun.)
- What colors absorbs more heat? (Hint: What colors of clothing feel hotter outside on a sunny day?) (Answer: Dark-colored objects absorb more light and heat energy than light-colored objects.)
- What happens when we place a shiny object in sunlight? (Answer: Shiny surfaces reflect sunlight.)
- What happens to an object's temperature when it is in the sun for awhile? (Answer: An object's temperature increases when it absorbs sunlight. This is a transformation of solar energy to thermal energy.)
- If we wanted to make sunlight shine on a particular spot on the ground and heat it up, what could we do?
Activity Embedded Assessment
- What are some reasons to use a solar cooker? (Possible answers. To save fuel, money and energy; to reduce pollution and emission of greenhouse gases; to reduce deforestation.)
- What is the transformation of energy that happens in a solar cooker? (Answer: Sunlight, in the form of solar radiation, is reflected, absorbed and converted into thermal energy.
- What are the important properties in a good solar cooker? What are their purposes? (Answer: Good reflection of light onto the cooking area, insulation to retain heat, dark cookware or a dark surface to absorb sunlight. Solar cookers have reflecting surfaces that direct the sunlight to one spot in the cooker. It helps if the shiny surfaces are adjustable. The best solar cookers also have clear covers and insulation to minimize the loss of the collected thermal energy. Some cookers have thermal mass to absorb and retain the collected thermal energy.)
- Engineers always want to improve the design of their inventions. If you were an engineer, how might you improve your solar cooker to work better? (Answers: Add a clear glass or plastic cover to trap heat; add insulation to keep from losing heat, add bricks or stones for thermal mass, put it on a revolving tray to easily be turned to track with the sun, etc.)
- Why might engineers be concerned about providing methods for people to use solar energy to cook? (Answer: Because some people do not have technologies such as ovens or stoves.)
- How could you take advantage of solar energy without special technologies or a cooker? (Possible answers: Dry foods in the sun, dry clothes in the sun, etc.)
- For younger students, precut the boxes for them.
- For lower grades, have the students design either the Box Panel Cooker or the Modified Box Panel Cooker, and take temperature measurements every five minutes instead of two.
- For upper grades, have students graph the temperature of the water in their solar cooker and the temperature of the control. Have students compare their graphs with teams using other cooker styles and determine which cooker design was the most efficient.
Catching Sunshine. Developed by Online Science-athon. Energy Science Projects and Activities. Energy Education and Training, Energy Efficiency and Renewable Energy, U.S. Department of Energy. Accessed November 28, 2005. (For grades 4-8, an activity to construct a solar collector, determining how to maximize the amount of sunshine it collects.) http://scithon.terc.edu/CatchingSunshine/
Constructing and Testing Solar Cookers. Renewable Energy Lesson Plans, Texas State Energy Conservation Office. Accessed November 28, 2005. (Activity adapted from this middle school lesson plan, click on #12 Cooking with the Sun) http://www.infinitepower.org/lessonplans.htm
Cooking with the Sun. Last Updated September 6, 2005. NASA. Accessed November 28, 2005. (Great instructions and photos for making a pizza box solar oven to cook a snack.) http://www.nasa.gov/audience/forkids/activities/A_Cooking_with_the_Sun.html
Dictionary.com. Lexico Publishing Group, LLC. Accessed December 20, 2005. (Source of vocabulary definitions, with some adaptation.) http://www.dictionary.com
Lindo, Natasha and Lerios, Toli. Physics of Solar Cooking. Engineering Group, Stanford Youth Environmental Science, Stanford University, CA. Found at Outdoors Physics, Umeå University, Sweden. Accessed November 30, 2005. (Source of background information) http://www.ccathsu.com/files/handouts/Parabolic%20Solar%20Cookers.pdf
Schleith, Susan and Sheinkopf, Blanche. Solar Matters III. Florida Solar Energy Center, University of Central Florida. Accessed September 18, 2006. (A solar energy science unit for grades 6-8). http://www.fsec.ucf.edu/en/education/k-12/curricula/sm3/
Solar Energy, Dr. E's Energy Lab, EERE Kids. Updated November 7, 2005. Energy Efficiency and Renewable Energy, U.S. Department of Energy. Accessed November 28, 2005. http://www.eere.energy.gov/kids/solar.html
Solar Energy Basics. Learning About Renewable Energy & Energy Efficiency, National Renewable Energy Laboratory. Accessed November 28, 2005. (Source of background information) http://www.nrel.gov/learning/re_solar.html
The Solar Cooking Archive. Solar Cookers International. Accessed March 26 2007. http://solarcooking.org
Student Resources on Solar Energy. Learning About Renewable Energy & Energy Efficiency, National Renewable Energy Laboratory. Accessed November 28, 2005. http://www.nrel.gov/learning/sr_solar.html
What's Cooking Teacher Information, Solar Matters III. Florida Solar Energy Center, University of Central Florida. Accessed September 18, 2006. http://www.fsec.ucf.edu/en/education/k-12/curricula/sm3/documents/SM3_WhatsCooking2.pdf
Xochitl Zamora-Thompson, Sabre Duren, Jeff Lyng, Jessica Todd, Geoffrey Hill, Jessica Butterfield, Malinda Schaefer Zarske, Denise Carlson
© 2005 by Regents of the University of Colorado.
Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Last modified: February 27, 2015