So this is the box that started it all. The famous oatmeal box. I made one for the Frog Princess (now almost 6 years old) when she was a toddler. It was a great way to keep her entertained in my kitchen while I cooked dinner or unloaded the dishwasher. Also a fantastic distraction when the weather outside is awful (winter and summer!) She loved it then and still loves it today. If she ate some of it, no harm no foul, it was just some extra fiber. I didn't introduce the sand table outside until this box was mastered and I knew the "tasting" stage was over.
I recycle fruit snack or pudding cups, detergent caps, and spice bottles for experiments with pouring and filling. It is great for hand eye coordination, fine motor development and serves as a great sensory experience. Both of my girls have a great time digging in. When they're done they get a little Montessori-style lesson in cleaning up with small dust pans and brooms. Don't be afraid of a little clean up at your house! It is a great learning tool and a gentle way to teach siblings how to play nicely together.
Go check out my old posts about my Ocean Box, Construction Box, and Winter Box. I just gave my favorite two year old up the street an Ocean box for her birthday last weekend and every kid (all ages from 8 years-22 months) dove into it for the next 30 minutes of the party. Same thing happened when I gave my other friend's little boy a Construction box for his birthday. Sometimes a box of rocks (or sand...or oatmeal) is all they need to have fun!