What are some invention ideas for a fifth grade class?

Invention ideas for a fifth grade class include a simple windmill and a stethoscope. The windmill is made of drinking straws and strong construction paper. The stethoscope uses a paper towel tube and a funnel. Another idea is building a balloon-powered car using common household and recyclable items.

A water xylophone made from empty glass bottles is an invention for musical children. Filling each bottle with different levels of water produces a variety of sounds when struck by a metal spoon. Students can be creative by adding food coloring to the water and experimenting with water levels and bottle sizes.