Your baby's mind is becoming as active as his body. He's having important insights about himself, the people around him, and his surroundings. He's smart enough to remember the past and anticipate the future. He's also smart enough to feel bored and lonely. He shouldn't be left alone in his crib or playpen for more than a half-hour at a time. He needs regular opportunities to move around, play with his toys, and interact with people.
Now and for years to come, you'll be his favorite teacher. Just look at how he studies your face when you hold him. If you stick out your tongue or open your mouth, he'll probably try to copy you. Take the game a step further by saying simple syllables such as "ahhh" or "ohhh" and watch him do the same. He thinks he's just playing copycat, but he's also developing important language skills.
He already knows a few words, including his name. Call him by name when you want to get his attention. "Hi" and "hello" can also be good conversation starters. Talk about anything and everything, but he'll be especially interested to hear the names of common objects. "Here's your blanket." "You threw the ball!" "How does that rattle taste?"
At his age, playtime is thinking time. All sorts of games can help get his mind humming. Here's a good brainteaser: When you have your baby's attention, show him a favorite toy, then put a blanket over it. Does he totally forget about the toy, or does he try to reach for it? If he seems to know where the toy is hiding, he has already tumbled to "object permanence," the idea that things don't disappear just because they're out of sight. This is one of the big mental leaps of infancy. If your baby doesn't seem to get the concept, give him plenty of chances to watch you hide and uncover toys.
Peek-a-boo is another great game for babies of his age. Since he's so interested in your face, he'll be fascinated to watch it reappear after disappearing behind your hands or a blanket. Somewhere between the giggles, he's getting yet another lesson in object permanence. After a while, you can start spending a little extra time in hiding. When he realizes that you aren't really gone, he'll probably start squealing in anticipation.
When he's playing with his toys, he'll explore every object in every possible way, taking note of its color, texture, sound, smell, and, of course, taste. More than anyone else in the house, he'll know the nuanced flavor differences between a wooden block and a teddy bear ear.
Give him toys that appeal to his senses and pique his curiosity. A soft, colorful ball is a fun way to learn about physics. He'll also enjoy plastic cups and blocks of different sizes. Read him books that he can explore with his hands. Books with fuzzy shapes -- such as the classic Pat the Bunny -- are especially fun.
Watch him closely when he reaches for a toy. If he's going for a ball, you'll probably see his fingers make a round shape. He'll prepare a different grip for his teddy bear and yet another grip for his rattle. He has already learned that different objects have different shapes, and he's thinking ahead about the best ways to pick them up.
Thinking can be hard work at this age. Still, he's making amazing progress every day, and no wonder. He has a great teacher.
Sears, William and Martha. The Baby Book: Everything You Need to Know About Your Baby From Birth to Age Two. 2003. Little, Brown and Company.
American Academy of Pediatrics. Caring for Your Baby and Young Child: Birth to Age Five. 2009. Bantam Books.
University of Florida, Department of Family, Youth, and Community Sciences. How I grow: Months five and six. August 2003. http://edis.ifas.ufl.edu/FY633
American Academy of Pediatrics, HealthyChildren.org. Cognitive Development: 4 to 7 months. http://www.healthychildren.org/English/ages-stages/baby/pages/Cognitive-Development-4-to-7-Months.aspx