The Magic School Bus - Season 4 Episode 3 -

The class is enjoying a normal summer day at the beach until Ms. Frizzle discovers a letter from ""Uncle Shelby,"" who wants the class to look after his beachfront property. The kids soon discover that this ""luxurious"" accommodation is only a tiny spot on the shoreline. Why would anyone want to live in a spot where they're battered by waves at high tide and baked by the sun at low tide? To find out, Ms. Frizzle turns the kids into... mussels!?