I love it when my kids think of something fun to do all on their own. They decided since it was so warm (not really but warmer), they wanted to throw ice. We decided to go outside for this. I gave them each a cup of ice, that we refilled several times, and we saw who could throw the farthest, watched it melt and cracked it into smaller pieces. Easy, quick, and fun. Although it is fall, is was warm enough to do this, but summer would maybe be even more fun. You could also color the ice.
Happy Playing and growing!