How to play: Make a silly noise, and see whether your baby imitates it. If he responds with a different sound, mimic it.
Why it's great right now: Around this age, a baby realizes he can move his lips and tongue to make a variety of sounds. Starting a dialogue teaches him that language is fun and stimulates his desire to speak and listen.
The next step: Try to connect your baby's babble with specific needs. Responding appropriately to his coos and grunts will confirm that his message got through.
Sit and Reach
How to play: Prop pillows to support your baby in a seated position. Place a colorful toy or a comfort object nearby, and watch her lunge for it.
Why it's great right now: This activity develops your child's trunk muscles as well as the balance and confidence she needs to stay upright on her own.
The next step: Help your baby sit up from a lying or crawling position. Eventually she'll try the movements herself.