Teaching a Toddler

My 21 month old son LOVES to learn. He could spend hours a day sitting with me doing puzzles, coloring, pointing out things in books, making animal sounds and more. He absorbs so much and we are constantly amazed at how much he knows and how fast he picks up on things. Lately, I've been trying to come up with some sort of organized plan for activities for him. However, I can't seem to find much information about what kids his age can understand right now. I have a list of things we need to work on such as colors, letters, numbers, etc..but I don't know when is too soon to start. Don't worry..I am not trying to make my 2 year old a genius who knows the presidents in order. (have you seen those kids on tv?) But he WANTS to learn things. He is constantly asking what things are, pointing at things and looking at me for a response, etc. So I want to teach him.

I want to be careful not to push him too hard or expect him to know things that he can't understand right now. I feel like he should be saying more things than he does. For example, he can point out every animal in a book, but the only ones that he'll actually say are dog and duck. Even simple ones such as cow he seems either uninterested in trying to say or he doesn't know how. He can point to the cow if you ask him or says "MOOOOO" but never tries to say it. I have no idea if this is normal for his age or not. So I want to learn more about this. About how to help him learn because he is inquisitive and loves learning with mom by his side. I just don't know where to go from here. If there are any education majors, teachers, or parents who have already been through this stage..I would love your input! Please share ideas, links to helpful websites, books, etc. My growing boy would definitely appreciate it!