The Primary classroom began a traditional Montessori study of the five classes of vertebrates (animals with backbones): fish, reptiles, amphibians, birds, and mammals. During these first two weeks, we studied fish. We read about the characteristics that define fish, such as living in water and breathing with gills. We conducted a science experiment with a coffee filter to see how gills work. The children explored many interesting fish activities and welcomed some fish visitors to the classroom.