easy ones to take care of
Radishes grow pretty fast, so they make good subjects for science projects. Mustard works well too.
Your school website is a good website to find a science fair project. Science programs for kids typically have websites with projects listed. PBS has a website for kids that includes science projects.
google.com or science fair projects.com
the growth of plants
breast
Decomposition, energy, light, electricity, and photosynthesis are all good science fair topics
grass plants are very good
I always loved coming up with science fair projects with my children while they were in elementary school. A good one for a third grader are playing two different kinds of music to two different plants to see which one grows faster and making a daily log regarding the plant and the music.
the way the plants die over winter for a week , Plants every where.....
i would call it something like plants galore!