9 - 24 Months: Drop It!
Living and Learning: At this age, your baby has played with enough toys to know that some things are hard, some are heavy, and some are yucky. Now he wants to know, What happens if...? Let's say you're preparing lunch for your almost-1-year-old and you've given him a toy car to play with while he waits. He knows that he can push it around on his high chair tray. So he throws it, and sure enough, it falls. When you pick it up and give it back to him, he wants to know, Will it fall again? Will I get the same reaction from Mom? By repeating this fun (for him) game, he begins to understand that he's causing the toy to fall, that it'll fall every time, and that Mom will probably keep picking it up -- and he revels in this discovery. "It feels good to know what comes next," says Stamm. "It helps us feel like we're in control."
Game Time: In the bath, give your baby cups of different sizes for her to fill with water and dump out. She's learning basic principles about the world, like shape (the cup is round) and size (the bigger cup holds more water). Give her blocks so she can make a tower -- then knock it down. By the time of her first birthday, your baby has the hand coordination to stack. And toppling it? Well, it's just fun to know she's going to make a mess.