There are hundreds of possible electronics science fair projects that you can complete. However, before you can develop an award winning science fair project that utilizes electronics you first need to understand the basic concepts of electronics.
Once these basic concepts are masters, through reading and basic projects, like the ones offered by the MX-907 200-in-1 Electronic Lab, you can apply these concepts to solving a problem. The problems that you try to solve will be revealed by your hypothesis. For example, if you are trying to solve the problem of feeding your dog when you are at school, you can apply electronics to develop a dog feeder that works on a timer.