We're getting ready to reciprocate a playdate with DD1's "best friend" from school. Usually for playdates with other friends, we just let the kids explore existing toys and activities at home, or meet at a neighborhood park. But, for our first playdate with this friend, the mom had purchased some slice and bake cookie dough, frosting, and sprinkles for the girls to do which I thought was nice. What are some other age-appropriate activities that I could have ready if needed?