1. Straw Rocket: Cut a straw into a pointy end and flat end, tape a piece of paper into a triangle, and slide it on the pointed end.
2. Balloon-powered Car: Make a car using cardboard, straws, and bottle caps. Attach a balloon to the back with tape.
3. Rubber Band Helicopter: Cut a paperclip in half and bend each piece into a "V" shape. Wind up the rubber band by twisting the "V" and watch your helicopter fly.
4. Homemade Air Conditioner: Fill a bucket with ice and place a fan on top, facing downwards.
5. Potato Battery: Cut two slices of potato and stick a copper wire in one slice and a zinc wire in the other slice. Connect the wires with a LED light.
6. Straw Bridge: Use straws and tape to build a bridge that can hold weight. Test it out with coins or other small objects.
7. Cardboard Marble Maze: Cut cardboard into different shapes and create a maze for a marble to roll through.
8. Tin Can Stilts: Use two tin cans and string to make stilts. Punch a hole in the bottom of each can and thread the string through.
9. Popsicle Stick Catapult: Use popsicle sticks, rubber bands, and a plastic spoon to make a catapult.
10. Egg Drop Challenge: Use household items to create a protective casing for an egg.
11. Homemade Water Filter: Use gravel, sand, and activated charcoal to create a water filter.