SPRING HILL — Mouths dropped as students walked through the door and were immersed in an underwater cave of the Florida aquifer, looking up at the mouth of a natural spring.Beyond the aquifer model was an equally impressive diaroma of the Florida wetlands, and a variety of hands-on environmental education exhibits and games, all in a 53-foot tractor-trailer transformed into WaterVentures, Florida’s Learning Lab. There were lots of buttons to push, knobs to turn and giant screens that oozed with environmental facts.The mobile learning lab recently visited Challenger K-8 School of Science and Mathematics two times: on April 11 for fourth-graders, and on April 26 for fifth-graders."It’s really cool," said fifth-grade student Grace Bartolomeo. "I feel like I can learn a lot in here.""I liked learning about the water cycle," said fifth-grader Joseph Rozsa. "It was cool to see how it evaporates ... The aquifer was my favorite."WaterVentures is a free resource through Crystal Springs Foundation that visits schools, fairs and other events throughout Florida, providing an innovative, hands-on experience on Florida’s watersheds, water conservation and recycling.After learning about WaterVentures nearly a year ago, elementary STEM lab teacher Leonette Ehlenbeck contacted the organization to arrange for the lab to visit."It came at a good time, just before FCAT science," Ehlenbeck said. "Not only are the students educated on water conservation, but they are empowered to become water stewards in their communities."Two environmental educators come with the lab, offering 20-minute programs at an outdoor activity center and an indoor exhibit. The outdoor activity center had two stations where students learned about watersheds, then created their own, using miniature people, trees and animals. Inside the trailer were museum-quality exhibits and learning activities."It was almost a year wait, but it was worth it," Ehlenbeck said. "This is something that all our schools should take advantage of. It’s like going to the museum."