The recipe is super easy, just three things- Water, play sand, and cornstarch.
The Little Misters LOVED it. We spent several hours building castles and other things. It's very stiff and yet crumbles nicely. We stored our Moon sand in a big zip lock, but the next day it wasn't as crumbly. I just added a touch more water and it was back to perfect again.
Definitely a outdoor activity, unless you enjoy cleaning up sand from... well everywhere.
Moon sand was a huge hit! Other recipes out there in PINTEREST land say you can make colored Moon sand, if that's more to your liking check out all these variations.