[niveabody]

Why don't you also try decorating your bb as if it is a big aquarium set up with colorful cut out fishes and corals. Make cut out fishes with real looking eyes (those stuff used for toys? you can buy them from a modiste stall)
Your students will really have fun with it! By the way on its border use red felt interconnected to highlight a rectangle aquarium. Have a great day and good luck!