The act of building a sandcastle on the ocean shore is as joyous as it is soul-crushing. You build, shape and sculpt that wet, gloppy sand into a grand structure, only to watch the tide roll in and dissolve all your hard work. Of course, you needn't head to the shore to experience sandy fun. Each summer the Magic House (516 South Kirkwood Road, Kirkwood) trucks in a few tons of sand and transforms a parking lot into Sandcastle Beach, a little oasis for the young'uns to enjoy the wonders of the beach without the threat of jellyfish or old men in Speedos. Sandcastle Beach runs through Sunday, August 5, and is free with admission ($7.50) to the Magic House. Call 314-822-8900 or visit www.magichouse.org for more information.