Memory or Concentration is a great game to teach little ones. With just a few cards very young children can learn the rules of play. As they get older or more adapt at the skill involved a more difficult game can be made by simply adding more cards.
To begin with toddlers, let's use circles of 8 to 10 different colors - two of each color.
To begin play, use only four cards, say the two red circles and two blue ones. Place the four cards face up on the playing surface. Point to a red circle and say "This is the red circle. Can you find another red circle?" If the child is correct let him collect both cards. If incorrect, gently tell him it is a BLUE circle and ask him to try again. Play with just the two colors face up until the child understands what the match is.
Then you can do one of two things...
1. Add another color and continue playing face up. Give the child a chance to do the asking sometimes as well and you make the matches.
2. Turn the four cards face down and turn up one card. Ask the child the color. Turn it back down. Then repeat with all four cards. Then again turn up one card and name the color. Ask the child if he remembers where the other red circle is. Let him collect the cards if correct and replace both cards if incorrect and continue playing. If this concept of having the cards face-down seems too overwhelming for the child return to face-up play, just adding more colors as the child seems to master the ones learned so far. Continue adding cards to each form of play as the child's skill level and ability increases.
I am sure that this reminder is not necessary but re-enforcing this game with books on colors, talking about colors, finding colors in your surroundings, naming colors of clothing and other items will make the child more quickly aware of the colors and their names.
Remember learning is to be fun. If the child is not enjoying the game, set it aside for another time. He may just be tired. Or he may not yet be ready for this skill or a game of this type.