Touching is okay at Portland's small but fun Children's Museum, where kids can pretend they are lobstermen, veterinarians, shopkeepers, or actors in a play. Most exhibits, many of which have a Maine theme, are best for kids 10 and younger. An outside pirate-ship play area is a great place to have a picnic lunch, and don't miss the life-size inflatable humpback whale rising to the ceiling at the whale exhibit. Have a Ball! teaches about the science of motion, letting kids build ramps that make balls speed up, slow down, and leap across tracks. Camera Obscura, an exhibit about optics, provides fascinating panoramic views of the city. It's aimed at adults and older children, so you can purchase a separate admission.