J.K.
At 2 and 3 if they don't already know the basics... you shouldn't try teaching them "formally". Use life experiences to teach them. Point out things they see everyday and tell them the color and shape. Then after doing this for a while you can start asking them what color or shape it is. There are also great flash cards that you can make up all kinds of games with that just have a shape on it. these shapes come in all kinds of colors and all the common shapes are there. Let them color with the colors they are learning and you can have them color or cut of pictures of shapes...even look through old magazines,etc to find common things that are the shape you are teaching (a mail box is a rectangle,etc).
The animals are pretty easy too. Get a bunch of animal books from the library (there are great color and shapes books as well). Look through them together pointing out the animals, talk about the sounds they make and where they live, what they eat,would they make a good pet?,etc. Take walks outside to see if you can see animals that would live near you and visit the zoo or if you have a nature center around you alot of them offer free programs for preschoolers and parents. You can also take walks and talk about the shapes and colors you see....flowers are really great for that.
There are tons of websites that offer free printables too. Enchanted learning is a good one and crayola has a bunch of stuff too. If they like videogame type toys the fisher price cool school is a great teaching tool and super fun. It teaches more than you mentioned as well so it can grow with them. Just make sure they are having fun and they will be learning it. If they are bored... you have been teaching too long or the wrong way and they are not getting anything out of it. Kids are sponges and they absorb everything they see. It is amazing how much they learn when you think they are just playing or watching TV (like dora and blues clues, mickey clubhouse,etc.
There is a computer game called Mickey Toddler that has mickey mouse and all his friends help the kids learn and play with shapes, colors, numbers, letters, music,etc. My girls loved it! And really picked up alot of knowledge just playing that game.They even learned what plaid was (since that was a color goofy used to paint his house). My youngest knew most of her letters before she was 2 from playing this game and picking up what her sister was learning. I didn't try to teach her anything she just knew it. She is that way now with spelling. She is 4 and asked the other day if you spell over o,v,e,r. Don't ask where that came from... i have no idea! Hope this helps, have fun and the kids will too :)