Categorizing Animals

Yesterday, Maya and I were working on categories of animals. She's getting very good. She knows that "mammals" are a kind of animal and that mammals have hair. For most mammals (bears, cats, dogs, horses, etc.), you can say "Maya, what kind of animal is a ___" and she will say some permutation of "It has hair, it's a mammal." She's actually pretty good at birds, too. "Maya, what kind of animal is a blue jay?" "It has feathers, it's a bird." But what was even better was learning about what makes birds different from other animals. It's that they have feathers, of course. But as Maya pointed out: "Mom, pillows have feathers!"