What would be a good science project for a 1st grader?

So my daughter just received her letter about entering her 1st science fair. I was wondering if anyone has any ideas on what are some good science fair projects for a 1st grader? She really wants to do something with the planets, so I’ve been trying to think of something that is not to difficult for a 1st grader to understand (she is very bright though). Would “what happened to the 9th planet?” (explanation on why Pluto is no longer classified as a “true” planet) be to complicated 1st graders to understand, as the parents we can guide them, I just don’t want to end up doing it for her. Again she would prefer doing something with the solar system, she thinks building the planets would be fun. Any ideas?