Pizza Box Solar Oven

What you need

• Cardboard box, 1 pizza box
• Paper, 1 sheet black paper
• Painter's tape, several strips
• Kid scissors
• Aluminum foil, 1 sheet
• Plastic wrap, 1 piece
• Stick or ruler, 1
• Crackers, 2 or 3
• Chocolate or marshmallows, 2 or 3
• Thermometer, 1 (optional)
• Pencil, 1

How to do it

Grown-up prep: Pick a clear, sunny day, ideally late morning to early afternoon. Help with the scissors when cutting the cardboard. Remind kids that the reflected light is bright, so they should not look straight into the foil, and that the box and treat can get hot.

1. Pick a sunny spot where the sun shines all hour.
2. Draw a flap on the lid and cut three sides of it. Ask for help if you need it
3. Cover the underside of the flap with foil, shiny side out.
4. Line the bottom of the box with black paper.
5. Tape plastic wrap tightly over the opening under the flap.
6. Set a cracker topped with chocolate or marshmallow inside.
7. Prop the flap open with the stick to aim sunlight inside.
   Ask: How long do you think it will take for the chocolate to melt?
8. Check every ten minutes and watch for changes.
9. Taste your treat carefully, then try again! What could make it melt faster?
   Ask: What would you change to make your oven even hotter?

Play it again

• Foil face-off: build two ovens, one with foil and one without, and see which melts a treat first.
• Temperature race: record the inside temperature every ten minutes and chart the climb.
• Snack menu: test which food melts fastest, like a marshmallow, cheese square or chocolate chip.