We are just in the starting stages of it, but we brainstormed lots of ideas for this years science project (he's in 7th grade) and he liked my idea best

He is going to grow 3 different brands of lettuce seeds (a cheap seed like Lilly Miller; a more reputable one like Territorial; an organic one from Abundant Life Seeds) and, under identical growing conditions, see which has better germination rates, grows quicker and produces a better lettuce plant.
I think it'll be an interesting experiment! I'll be sure to post his results.