|Ice rafts on Europa (photo from JPL)|
If you are not so careless about your kiddie pool, or if your kids have outgrown the small wading pool stage, you can use any shallow basin. Fill it with the remnants of the latest snow storm, and let it melt a bit in the shade and freeze again overnight. It should be a bit bumpy on the surface, and may be still unfrozen below the surface. Toss a small stone onto the surface. If nothing happens, try a larger stone, until the impact breaks the surface and the stone falls through the ice. Watch the water well up from beneath the ice, and check it the next day (after a decent overnight freeze), and you ought to see a similarity to the young surface of Europa. (Compare with our moon: A young surface on our moon is smooth from relatively recent lava flow.)
If the temperature conditions are just right, you might even get a fine crater-shaped hole in the ice, complete with a ridge and ejecta debris. As long as the cycle of freezing and thawing continues, you can continue to experiment.