Fun with hands
By the third month, your baby will spend a large amount of time entertaining himself with his hands. Most of the time, his hands will be open. The act of opening and closing them, as well as staring at them, will be almost as fun for your baby as exploring his stuffed animals.
While it may look like its all fun and games, your baby is also working on strengthening his hand muscles. In five to six months, he should be able to pick up toys. To help him along, put a rattle in his hand, and gently tugs on it; this also helps him build muscle.