GSCCC Girl Scouts At Home

Make s’mores with the sun! Follow the instructions to make a solar oven.

What You’ll Need:

• Cardboard pizza box (the kind delivered pizza comes in, or similar)
• Aluminum foil
• Clear tape
• Plastic wrap
• Black construction paper
• Ruler, wooden spoon or stick
• Graham crackers, chocolate bars, marshmallows

What You Do:

• Cover the inner side of the top and bottom of the box with aluminum foil so that it will reflect rays from the sun. To do this, tightly wrap foil around it, then tape it to the back, or outer sides.
• Line the bottom of the box with black construction paper where the s’mores will be placed— black absorbs heat.
• Place the s’mores ingredients in the box as shown in the picture.
• Use clear plastic wrap to create an airtight window for sunlight to enter into the box. Do this by opening the box and taping a double layer of plastic wrap over the inside of the box as seen in the picture above. Leave about an inch of plastic overlap around the sides and tape each side down securely, sealing out air.
• The best hours to set up your solar oven are when the sun is high overhead - from 11 am to 3 pm. Take it outside to a sunny spot and adjust the flap until the most sunlight possible is reflecting off the aluminum foil and onto the plastic-covered window. Use a ruler, wooden spoon, or stick to prop the lid at the right angle.
• Reposition your solar oven when needed, so that it faces direct sunlight. You should check periodically on your oven to make sure it is in the sun. Make sure that the foil-covered flap is reflecting light into the box through the plastic-covered window.
• Wait until the chocolate gets soft and the marshmallows are warm and toasty. Then peel back the plastic, combine the s’mores together and enjoy your warm, tasty treat from the sun!

What Happened?

The heat from the sun was trapped inside your solar oven, and it got very hot in there. Ovens like this one are called collector boxes, because they collect sunlight. As it sat out in the sun, your oven eventually heated up enough to melt the chocolate and marshmallow!

How does it happen?

Rays of light are coming to the earth at an angle. The foil reflects the light ray and bounces it directly into the opening of the box. Once it has gone through the plastic wrap, it heats up the air that is trapped inside. The black paper absorbs the heat at the bottom of the oven, and the plastic wrap keeps it from escaping out the sides of the oven. Your solar oven will reach about 200° F on a sunny day, and it will take longer to heat things than a conventional oven. Although this method will take longer, it is very easy to use, and it is safe to leave alone while the energy from the sun cooks your food.