This is pretty cool. Orb.Farm lets you run your own biosphere, adding materials as you like to see their affect on your own little world. There is a lot here to use, especially if you are teaching science and biomes.
The built in help describes everything that can go in to your biosphere and what affects they will have on the biosphere. As the world lives, the sun will rise and set in the background. My only complaint is that I haven’t found a way to figure out how many days your biosphere has survived.