The pinewood derby is a racing event for Cub Scouts. Cub Scouts, with the help of parents, build their own cars from wood, usually from kits containing a block of pine, plastic wheels, and metal axles.
 

Car Construction

The Scout is given a block of wood made of pine with two notches for wheels, four plastic wheels, and four nails. The finished car must use all nine pieces, must not exceed a certain weight, must not exceed a certain length, and must fit on the track used by that particular scout pack.

Pinewood Derby Kit

Blocks can be whittled with a hand knife or cut with a bandsaw or Dremel carving tool for major shaping. You can purchase decals at scout shops or hobby shops. 

Other than the previous basic design rules, the Cub Scout is able to carve and decorate the car as he chooses. Many Cub Scouts also add weights to the final design to bring the car to the maximum allowable weight; coins, glue-in lead pieces, and melted lead are common ways to add weight. Cars typically vary from unfinished blocks to whimsical objects, to accurate replicas of actual cars. Graphite is usually the only lubricant allowed, and it often helps to polish the provided axles.

The idea behind the pinewood derby is for the parent to spend time helping the child design, carve, paint, add weights, and tune the final car. It is important, however, to remember that the parent is the helper and the child should be doing as much of his own work as possible.

Competition

The track usually has two to six lanes and slopes down to the ground, since the cars are powered by gravity. Tracks may be owned by the pack or rented. The race is run in heats, giving every car the chance to run on each lane. The racers can be grouped with others from the same rank (Tiger Cubs, Wolf Cubs, Bear Cubs, etc.) or can compete against the pack as a whole.

The first, second, and third place winners usually receive ribbons, medals, or trophies. Some packs also award on the basis of car design. The first place race winners get to advance to the district level, then each of the district-wide race winners get to race each other from across the entire council.

Wooden Pinewood Derby track

More information

The web is full of a bunch of information about building cars and tips for designs. Remember though, the event is about doing a special activity with your child, teaching your child, and boosting his creativity. Here is a link to one basic site to help get you started.

http://home.simplyweb.net/bosworth/howto.htm

Good luck and Most of All - Have Fun!