Children are fascinated by animals--they're big, they're small, they're furry, scaly, slippery, feathery, and endlessly awe inspiring. Looking at pictures or watching a video might be interesting, but to really get your little ones engaged, use hands-on lessons to teach children animal classification.
Collect pictures of animals either by cutting images from magazines or printing from your computer. Trim the edges and paste them on to index cards. Ask the children to put them into groups--what they do might surprise you. They might cluster them according to size or color, but work with them to put them into animal classification categories. If you have two of each animal, you can play a matching or memory game.
Set up a felt board that is segmented into thirds with a large, blue area at the bottom of the board, a green area spanning the middle section and another light blue area near the top third of the board. Talk to children about the different kinds of animals and where they spend most of their time--in the water, on land, or in the sky. Provide a selection of animal cut-outs that children can move around on the board. Cut-outs can be simple felt animal shapes or pictures that you've laminated and affixed Velcro to the back.
Pour an inch of sand or beans into a large under-the-bed storage container. Give children a basket full of tiny plastic animals and allow your child to move them around and organize them in the sand. Put water into a shallow plastic dish and position it in the sand. Encourage your little one to drop in tiny plastic fish and sea animals.