OK a bit messy, but lots of fun! Make your own edible finger paint for the kids. Its cheap to make and safe to use and if theres any left over, store it in the fridge or freezer to use for another day.
Do your kids love to dance? Have a little ballerina whos begging for lessons? Music and movement or preballet classes provide a great early introduction to ballet for toddlers and preschoolers and offer many physical benefits too.