When classifying organisms, there are 6 Kingdoms, or categories.  This book goes over each one!

Animals

The largest kingdom of the 6 is animals, with over 1 million known species.  All animals are made up of many complex cells. Animals are found all over the world in so many diverse environments.  

Plants

The second biggest kingdom is plants, with over 250,000 different species.  Plants can vary from tiny flowers and grass, all the way to massive trees.  Plants are autotrophs which means they make their own food.  

Fungi

The next kingdom of organisms are called Fungi, like mushrooms, mold, and mildew.  Fungi cannot make their own food, so they must get their food from parts of plants that are decaying in the soil.  Most fungi are multicellular.