This is my favorite sensory play to date, hands down. Moon sand (otherwise known as cloud dough or moon dough) is super simple to make and so much fun to play with.
Mix 4 cups of flour with 1/2 cup of vegetable oil or baby oil (I used vegetable). The result is a silky and moldable sand! My kids played with this for hours.
*Word of warning: do not let your kids play with this while they are wearing knits. You will not be able to get the sand out and it will harden into a glue like substance after drying that will not come out in the wash. I learned this the hard way. Amelia had to donate her leggings and socks to the trash can.