Typically, third-graders are assigned to invent when they learn about simple machines such as levers, wheels, pulleys and wedges. Finding a way for these simple mechanics to solve an everyday problem is a fun project with vast possibilities. Look for common household problems that a third-grader faces, such as reaching high shelves and staying organized. One idea is to design a pulley system to bring items on high shelves lower. Another is a wheel-based storage unit, built from a rotary toolbox, to keep school supplies in order.
Games are a fun invention. Third-graders can take cues from their favorite board games and rework the goals to suit their assignment. A game based on an existing board game map is a place to start. A student may create cards with science terms on them, the answer either moving the piece along the map or earning points or coins. A game that illustrates some scientific process the student has learned about, such as photosynthesis, provides the chance for fun graphics and a greater understanding of the subject.
For third-graders who love to read, inventions that contribute to their experience with the written word might fire up their imaginations. Once they have learned how to make a battery power a light bulb, the possibilities abound for design. One potential idea is a light switch based on the cover of a favorite book. Another example of an invention is book covers with built-in bookmarks or notepads.
Keeping clean is part of everyday life for third-graders. A pair of shoes that fit over regular shoes, allowing for play outside of church or school without having to change, is one potential invention for a third-grader. A special toothbrush storage rack with space for paste and floss is another possibility. A combination hairbrush/hair clip storage box, or some other device that keeps items close together, may lead to creative inventions that save time in the morning.