Popcorn! (and the 5 senses)
I found the idea for a Popcorn Investigation from this preschool science ebook from Scholastic. I made a quick little zine for L to record her findings, and we set to work on the kitchen floor. You can use my little book if you want to try it yourself.
We made popcorn the old fashion way - on the stove in a pot - and paused during each step to use each of our five senses and record what we found. I can't think of a better project that uses all 5 senses in such a fun way. In hindsight, this would have been good way to start of our science studies. It was a blast looking at our blue popcorn, sticking our fingers in the oil, listening to the popping, smelling the butter, and of course, eating the popcorn.