Any object that baby can turn into a toy will teach him a thing or two.

Learning While Playing
Playing with your baby may seem like all fun and games -- shaking rattles, squeaking plush animals, and watching as your child tries his chubby hand at rolling a ball. But make no mistake: What looks like downtime is work to little ones, and toys are often the tools for getting the job done.

Newborns and Up
Shake, Rattle, and Roll
The classic first toy, a rattle gets baby's attention when shaken.

Newborn to 10 months
Gym Time
A takeoff on the mobile, activity gyms typically feature a charming, brightly colored floor and hanging detachable toys that make sounds, play music, and sport tantalizing textures.

4 Months and Older
I See You
Playing peekaboo -- hiding your face behind your hands and peeking out at baby -- is an exciting game.

4 to 15 Months
The Big Bang
Shaking, throwing, dropping, and especially whacking toys against a surface is how your baby experiments. "Babies love to bang," says Maureen O'Brien, PhD, director of child development at The First Years corporation in Avon, Massachusetts.

6 Months and Up
Having a Ball
Round and bouncy, a ball is the toy that keeps on giving.

8 Months and Older
The Nesting (and Stacking) Instinct
Nesting blocks and cups and stacking toys keep little hands busy.

8 to 12 Months
Free-Fall
No doubt, by the second half of baby's first year, she will repeatedly drop things from her high chair -- a spoon, her bottle, or her sippy cup -- and squeal with delight when you fetch the objects...again and again.

8 Months and Up
Sorting It Out
Starting at about 8 months, your baby will be able to grasp objects with her fingers and put smaller toys into a bigger one, such as a ball into a box. At around age 1, she will be able to put triangles, circles, and squares through their designated slots on a shape sorter.

1 to 2 Years
Fill 'er Up
Turn your back and you're likely to find your toddler emptying the salt shaker or overturning the dog's dish. "My daughter loves to take the wash in and out of the laundry basket," says Katrina Blauvelt of Marietta, Georgia, mother of 1-year-old Eva.