In the early 1900s, kids used soap boxes to create cars for downhill races. These days cars are constructed from shiny kits and the soap box derby is still popular with kids across the country.

But before your child zooms downhill at what passes for breakneck speed in a vehicle with no engine, make sure he (or she) is protected from scrapes, bruises and head injuries. Because this time, he's the one in the driver's seat.

"A young driver has been told all his life what to do, when to do it and where to do it, but when he gets into his car at the top of the hill and the paddles drop, he's in complete control," says Brian Graham, the All-American Soap Box Derby (AASBD) regional director for California, Nevada, Utah, Arizona and Hawaii.

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A soap box derby is "one of the few places children and parents are working toward a common goal,” says Graham. “It’s also empowering for the child."

Camps and schools are now teaching kids how to make soap box cars as part of the STEM (science, technology, engineering and mathematics) curriculum. "We have a new generation coming to soap box derbies from the STEM programs. We've always taught racers about engineering, bolt tension and so on," says Graham.

Although girls were prohibited from the AASBD soap box derbies until 1972, Graham notes they're now on a roll, accounting for more than 50 percent of participants.

If you have a budding racer, here are some tips for safe races and practices, courtesy of the AASBD.

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Bring him up to speed slowly. Make sure your child can control his car even when he's going really fast. “If that means starting him half-way up the hill and letting him go down it until he’s ready to go higher, that’s fine,” says Graham. Teach him safe driving practices too. For example, over-steering can lead to a spin-out or cause a car to hit the guard rail.

Tell him to keep his hands on the wheel. “After the great push to cross the finish line, kids are so thrilled they'll throw their arms up in excitement," says Graham. "We have all kinds of safety barriers, such as bales of hay, that will stop an out-of control car. That way exuberant kids can be exuberant without getting seriously injured.” But it still pays to keep steering until the car comes to a stop.

Teach him to wait until the coast is clear. That means making sure there are no pedestrians on the track before he shoots down it. Since a soap box car doesn't have an engine, it can be so quiet a person might not hear it approaching.

Let him know its OK to stop if something's wrong. “We tell kids all the time if they need to stop for whatever reason, just stop — it won’t be held against them,” says Graham. If an animal gets onto the track, he gets dust in his eye, his helmet comes loose or something just doesn't feel right, your child should feel comfortable putting on the brakes.

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Let him know wearing a helmet is non-negotiable. This includes during practice runs. Check to make sure his helmet is strapped on properly. It's the only way to protect his head as fully as possible if he crashes or is ejected from the car.

Fine-tune his racing attire. Open-toe shoes are not appropriate. Your child's footwear should have a sole with a good grip to decrease the chance his foot will slip when he brakes. Long sleeves also are a good idea. They'll add a bit of skin protection in a crash. Shorts are okay, though. They used to be verboten since homemade cars sometimes had exposed nails or other things that could scratch bare legs. “Now that cars are made out of kits, you don’t have to wear long pants anymore, which is probably good if you’re racing in 90 or 100 degree weather,” says Graham.

Alyssa Hauguel is a freelance writer in Sacramento, California, with a passion for health, family and consumer finance stories. She has also worked in hospitals and other health care settings as a medical assistant.