Pre-schoolers at the Bronx Works Early Childhood Learning Center got a hands-on lesson in underwater creatures right in their own classroom.The students watched trout hatch from eggs and grow into small fish. Today, the youngsters sang songs to say goodbye to their fishy friends as they prepare set them free in a stream.The unique learning experience is part of a pilot program called Trout in the Classroom. It's designed to teach children in an urban setting more about watery habitats.