To introduce note values to my students I use graham crackers, chocolate chips and marshmallows. The grahams are already conveniently divided into 4 sections. Each rectangle represents one beat. Then we add the chocolate chips and pretzels to make quarter notes on one cracker or marshmallows & pretzels to make half notes on 2 crackers. This helps kids visualize that half notes are bigger and therefore longer. Once they have successfully "clapped" the rhythm on their crackers, then they get to eat them.
Click on the music learning community link to play this quick game to review quarter notes and half notes. It may be a challenge for some young students to control the mouse quickly enough, so you can have them point to the correct answer on the screen or call it out while you click on it.
Check out this fun game on the Music Learning Community link to introduce the white keys CDE to your child. I introduce "D" first by having them find the 2 black key groups and saying this little rhyme - "Hey Diddle Diddle, the D's in the middle." Another fun way is to call the 2 black keys the Doghouse and tell them that the "D" for Dog lives inside, but for young preschoolers who may not associate D with Dog yet, this analogy won't be very effective.