Solar Ovens-Part 2

Objective

The second lesson asks the students to finish their oven and apple slices are baked for several hours. Discussion about the requirements for successful cooking with a solar oven. The results of their experiment are recorded.

CA Standards--Second Grade

• Records data in a systematic way

CA Standards--Third Grade

• Measuring Matter Module--Foss
• Sun, Moon, and Stars Module--Foss

Materials

Finish making the solar oven in Part 1.

• Materials for making solar oven
• Meat or other kind of probe thermometer (either digital or analog)
• Apple slices (I used pre-cut ones), kept ice cold in a small cooler

Procedures

1. Reviewed why one would want to use the sun to cook.
   • Good for the environment, readily available in many climates, keeps your house cool in the summer, doesn’t require fire/fuel, etc.
2. Discussion with students about why and when solar cooking will not work..
   • Sunny day with minimal clouds, must turn toward sun and frequently adjust, have to monitor for shadows.
   • Used this page to illustrate how solar cookers work and different designs.
3. Collected the ambient air temperature with thermometer in the sun and also the temperature of a piece of apple. Recorded data, including time, on worksheet.
4. Give students 1 slice of apple to eat. Ask them to note how cold the first slice is as they eat it. Give them a small piece of light-weight tin foil and a second slice of apple to use for the experiment. Place the foil under the apple so the bottom of the oven stays clean.
5. Leave the ovens in the sun for several hours. Show the students how to face them towards the sunlight and direct the reflector onto the apple in the bottom of the oven to avoid shadows. Point out the expected direction of travel of the sun as it moves through the sky. Advise the students to move the ovens periodically when they go outside, like at breaks.
6. Discuss as a group how to make ovens more efficient and completed the worksheet. Factors that can affect the speed of cooking include the time of year, the amount of sun, the amount and size of food, and the type of pot.
7. Towards the end of the day, check the temperature of the apples. Do not open the ovens until just before you are ready to test the student’s individual apples. The heat from the ovens dissipates rapidly, leading to the apples cooling shortly thereafter.
8. The children, either as homework or in class the next day, worked on improving their oven design. Class room discussion about the results showed the following:
   • Those that were in the sun the longest, got the hottest.
   • Boxes turned more towards the sun had a higher temperature than those that ended up being more shaded.
   • Dark colored boxes or those that the children covered in black construction paper were warmer.