Egg Cartons suggest math to me. I think it's all those nice even compartments. Even before I joined the Recycle!Create! group I had already done a skip counting practice activity from an egg carton.
My four-year-old daughter absolutely loves it, and even asks for it when it's put away.
Apparently, I am not the only one who thinks math when trying to re-use old egg cartons. Take a look at these great projects that I found on the Recycle! Create! Link-up.
Color Sort from Powerful Mothering
Number Exploration by Sparkle and Pook This is an introduction to counting.
Counting Activity from an Egg Carton by There's Just One Mommy This one is to practice counting.
A Ten Frame by Teaching Every Day Would be great as an introduction or review of counting to 10, and I love her detailed explanation all the benefits from this activity!
Mancala from Marie's Pastiche I was going to do this until I came across her post. I am glad she linked it up because she has a fantastic explanation of the game's background. You can try this with wee little ones and it challenges adults too!