Ishaan school in UK was a good learning. They introduced the aquatic animals in water (just a little in a box) and left the kids to explore them. I think it made easy for him and his friends to know that they live in water. They were toy animals like fishes, octopus, frog, whale, shark, and others. Likewise, it is easy to introduce animals to kids 🙂
For farm or cattle animals, they had provided old mac donald’s farm house kit. If you don’t have it, still can make a set up of a small house, with other natural plants and keep all animals in the scene. In this we can introduce cow, horse, sheep, pig, goat, buffalo, hen, and others. If possible we can even visit a farm where kids can spend some time and learn about them.
To introduce wild animals, we can visit a zoo nearby. It is the most effective way for kids to enjoy and learn about it. Off course it will be an outing for us. Here we can see lot of birds and other species too. We can even visit a museum (if available) in your town. For Ishaan we were lucky enough to visit the National History Museum (all animals which includes dinosaurs) in UK.
Seeing and feeling the toys makes it more easy to learn than just in books or online.