Remember when you were a kid and you spent the entire weekend outside playing? Well, those childhood games can actually help get and keep you in shape. Here are a few popular children's activities, how to play them, and their benefits.

HOPSCOTCH

Benefits:

According to Mieke Scripps, a physical therapist for the Miami City Ballet, hopscotch is great for balance and strength. Hopping works all the leg muscles, and when on one leg, the core or center muscles will be challenged.

Bending down to pick up stones while on one leg is also great for balance and gluteal strength. In fact, hopping may improve "overall lower extremity mobility given the different movement planes (forward-back, sideways and rotational)," says Fabio Comana, an exercise physiologist for the American Council on Exercise.

What you need:

Chalk or masking tape, a sidewalk, safe street and/or flat surface and a stone.

How you play:

Using chalk or masking tape, draw the following: a single box with the number one in it, then two boxes side-by-side centered right above that box. Label these boxes "2" and "3." Next draw a single box, centered above the "2" and "3" boxes. Label it "4." Continue with two more boxes labeled "5" and "6," one centered above those labeled "7,", and finally two more - "8" and "9" - with a semicircle or half-moon at the top.

You need two or more players. One person starts by tossing a stone into the first box. If you miss the box, you lose your turn. If the stone falls in the box, you get to go through the hopscotch course putting only one foot in each box. This means you alternately hop on one foot and land on two feet side by side. Skip the box with the stone in it along the way.

The idea is to go through the entire course without losing your balance. After you get to the top, you turn and head back down the course picking up the stone when you come to it. If you complete the course without falling, stepping on a line or missing one of the boxes, you throw the stone to the next numbered box and repeat the process. If you don't complete the course, you must wait your turn and then start in the box where you ended your previous turn. Whoever completes the full course first wins.

How many calories you burn:

About 5.9 calories per minute and 175.8 calories per half-hour.

FLYING A KITE

Benefits:

While it's not much of a cardio workout, kite flying offers "scapular stability on the side you are flying. It also builds core strength and balance to stabilize the kite in strong wind," says Scripps. But keep in mind that the "constant upward gaze might aggravate neck problems for some people," adds H. James Phillips, of the School of Graduate Medical Education, Seton Hall University.

What you need:

A kite, wind, a wide open space.

How you play:

According to David Gomberg of Gomberg Kites in Oregon, "Stand with your back to the wind and hold your kite up as high as you can. Make sure the nose is pointing straight up, and then gently let it go. If the breeze is strong enough, the kite will start to rise. Slowly let out a little flying line, and the kite will fly back. Then, before it reaches the ground, tighten your grip on the line and the kite will start to rise again. Repeat this until the kite gets up into steady winds."

In lighter winds, have a friend hold your kite about 50 feet away and release it into the wind as you pull in on the line. The kite should shoot up into the sky. When you get a little height, let out more line, then pull in again to gain altitude.

Buying a kite? There are many types. Each is designed to do something different in the sky. Gomberg recommends that beginners go with a simple design like a Delta Kite. "Look for a kite 5- to 7-feet wide and made of durable, lightweight materials. Expect to spend $20 to $30," he adds.

How many calories you burn:

:

About 3.5 calories per minute and 105.5 calories per half-hour.

MUSICAL CHAIRS

Benefits:

Great for agility, reflexes and balance, says Scripps.

What you need:

Chairs, a semi-open space, someone to manage the music.

How you play:

Move some furniture to clear some space. Then arrange five or six chairs (depending on the number of players) in a circle with the seats facing outward. To be fair, all the chairs should be of the same type. You must have one less chair than the number of participants. The music starts, and the group walks around the chairs. When the music stops, everyone vies to sit in a chair. The player left standing is out. Eliminate one chair and start over. Keep taking away chairs until there is only one chair and two players left. The one who gets the last chair wins.

How many calories you burn:

About 5.9 calories per minute and 175.8 calories per half-hour.

SEESAW

Benefits:

"It works the quads, hamstrings and calves for pushing off, hamstring and calf eccentrically when landing, and the up-and-down motion is good stimulus for the vestibular system, which helps with balance," says Scripps.

What you need:

A long, narrow plank balanced perfectly on some sort of center piece. You can also buy a seesaw or build one with a kit (www.7thpeak.com).

How you play:

A seesaw needs two people. One person sits on each end, and then you start. One person pushes off the ground while the other is automatically lowered. That person then pushes off, and the one opposite is lowered. This continues until you get tired.

How many calories you burn:

About 2.9 calories per minute or 88 calories per half-hour.

*Based on a 155-pound person.

Charles Stuart Platkin is a nutrition and public-health advocate, and author of "Breaking the FAT Pattern" (Plume, 2006). Sign up for the free Diet Detective newsletter at www.dietdetective.com.