Create something new to wear with an invention that improves on an existing piece of clothing. Maybe add a hood to a dress to fulfill a specific need. (Get help from a parent sewing the hood.) Shirts and jackets usually often sport zippers, buttons or snaps. Invent a new method for fastening shirts and jackets that is easier to use and more fashionable.
Be the king of your schoolyard with a new sport that takes the best elements of the sports you already enjoy. See if you can come up with a game on a tennis court that uses a Frisbee instead of a ball, for example. Otherwise, invent a new piece of sports equipment that improves your play. Baseball players might appreciate a bat with built-in finger grips, for instance.
Make home life easier for your parents with a dishcloth that changes color when it needs to be washed. Invent a sponge with a hollow center that can be filled with soap, or a dinner plate with foam padding that will not break even when dropped. Make household chores easier with a new way to pick up after your dog, or a storage system for garbage that kills odors.
Invent something that will make you the most popular kid in class. Create a website that allows students to share homework ideas. (Ask your teacher first, and make sure it can't be used for cheating). Or invent a pen that has a liquid paper dispenser attached to it, or a combination pen-and-pencil.