STEM Activity: Sweet and Sunny Solar Oven

The summer season encourages us to think about the sun’s benefits, like how it warms the Earth – causing wind and weather – and helps humans, animals and plants sustain life. Solar energy, a product of the sun, also can be harnessed to help humans with innovative solutions to specific needs and challenges.

With this sweet activity that combines sunshine and chocolate, you’ll explore a fun use for the sun's energy and create a solar oven to make tasty treats.

Materials Needed:

• Aluminum foil
• Black paper
• Bowl or dish
• Chocolate bar or pieces
• Chocolate molding trays
• Clear plastic wrap
• Oven mitt
• Pencil or ruler
• Pizza box (clean)
• Tape
• Scissors

Step-by-Step Instructions:

1. Research different types of solar ovens by doing an internet-safe search online.
    
2. Using your scissors, safely cut a flap in the lid of your pizza box. Be sure to leave space on the sides of the box.

3. Fold the flap upward so it stands on its own and exposes the interior of the pizza box.
    
4. Wrap a piece of aluminum foil around the flap of your pizza box so it covers the portion that is directed at the inside of the box.
   
   Secure the aluminum foil with tape to the backside of the flap.
    
5. Open the pizza box and tape clear plastic wrap tightly over the hole in the lid to seal out air.

6. Next, line the bottom of the inside of the pizza box with aluminum foil, securing it to the box with tape.
    
7. Tape black paper on top of the aluminum foil to absorb heat from the sunlight.

8. Then, put your chocolate bar or chocolate pieces in a bowl or dish that is shallow enough to fit inside the pizza box when it is closed.
   
   Place it on the black paper and close the lid of the pizza box.

9. Use a ruler or pencil to prop open the flap of your pizza box, and leave the box outside in the sun.
   
   Be sure to angle the box so that the sunlight is reflecting off the aluminum foil and onto the plastic wrap.
    
10. Once the chocolate has melted, use oven mitts to take it out of your solar oven.
     
11. If you’d prefer to eat some chocolate while it’s still warm, try pouring it over ice cream or salty snacks!
     
12. To make a cool treat, carefully pour your chocolate into molding trays of your choosing.
     
13. Place the molding trays inside your refrigerator to cool down.
     
14. After about 30 minutes in the refrigerator, the chocolate will have hardened, and you can remove the pieces from your mold to enjoy another sweet treat on World Chocolate Day!

What Are We Discovering?

Your solar oven works by reflecting rays of sunlight off the aluminum foil and into the box through the plastic window. The heat from the sun becomes trapped in the box, warming the air inside and melting the chocolate.

Many inventors have found ways to harness and use the sun’s rays, like National Inventors Hall of Fame® Inductee Mária Telkes, who invented solar thermal storage systems that can store energy from the sun and put it to practical uses, like in solar ovens.

Thanks to Inductee Mary Engle Pennington, who devoted most of her career to the study of refrigeration, you can place your chocolate in the refrigerator to solidify quickly.

Keep the Fun and Learning Going!

For more at-home, hands-on STEM activities to try this summer, visit our blog.