My two year old son needed some help learning colors, so I decided to make something tangible that he could hold and feel while memorizing their color. I grabbed little odds and ends (pictured above) and put them in individual baggies. He gets to open a bag and get out all the green and notice the different shades, and lay them all out, and then put them back in the bag. He did so well with this, and learned them pretty fast. You'll be surprised at all the little colored things you have lying around. My favorite is the army men since they come in three shades of green.