Doing a project for presentation at a science fair has some obvious benefits.
Students learn about subjects of special interest.
They have the opportunity to be part of an event that puts their work on display and they can meet other students with similar interests. There are many sources to use to come up with ideas. Use as many ways as possible to come up with ideas. Magazines - Check the table of contents in magazines, especially science magazines to see what leading researchers are doing. Family - Talk to family members, neighbors, and friends about their work and how science plays a part in their lives or could influence their lives.