Here is information about many common animals found in Michigan, and a few that live in other places. You could find many of these animals in or around your schoolyard. Remember that this is just a little bit of animal biodiversity. There are many many other kinds of animals in other places. If you want to learn about animals that don't live in southeast Michigan, you can go to the Animal Diversity Web.
Mammals, birds, reptiles, amphibians, and fish are all vertebrates - they have a "spinal column" made up of many bones.
While vertebrates are more familiar to most people, there are many, many more species of invertebrates. In Michigan alone there are over 20,000 species, mostly insects, but also snails, clams, worms, arachnids, crustaceans, and other creatures. There are many more that have never been seen and are still unknown to science. Around the world, there are millions of species of invertebrates. Most of those invertebrates are insects. In comparison, the number of vertebrates is closer to tens of thousands.
For simplicity's sake, we have presented six main groups of invertebrates, distinguished by the number of legs they have.