Do you dash out to a field to play soccer or football after school? Do you head for a gym to play basketball or practice your gymnastics moves? Do you dive into a pool to swim laps?

Many of you probably take part in these and other after-school sports. You're not alone! The National PTA (Parent Teacher Association) reports that 20 million children between the ages of 8 and 16 play organized sports outside of school.

It's great to take part in an organized sport. It's good for you both physically and emotionally. More than that, it's fun.

But sports can be risky, too. For example, doctors in emergency rooms around the country treat about 40,000 sports-related injuries every year.

In 1986, some 636,000 high-school students suffered football injuries. Around 10 percent of these were serious enough to keep the players sidelined for more than three weeks.

The National PTA has declared November 1987 "Child Safety and Protection Month." Because so many kids play sports, an important part of child safety is keeping kids from getting hurt on playing fields, in gyms, on ice rinks and in swimming pools.

Here's a sports safety quiz. The questions will help you decide if you are doing enough to protect yourself when you play sports. :: Do I wear the right equipment for my sport?

When you play contact sports -- activities in which you're likely to be bumping into other players -- you should wear appropriate eye, head, face, mouth and body protection. For example, you should always wear a helmet with a face shield when playing hockey or baseball. The equipment should be in good shape. It should fit you. Don't wear clothes or equipment from last year that don't fit any more or have worn out. :: Do I go to my doctor for a yearly physical?

Your family should make sure that you see a doctor once a year. He or she will be able to determine whether you should take part in a particular sport. When you go to your physical, make sure you tell your doctor if you want to play soccer, football or become a speed skater. You might get some good advice about how to get in the best possible shape for your sport. :: Do I drink water before, during and after sports practices and events?

Don't forget to keep your body well supplied with water. Playing sports puts unusual demands on your system. Active sports make you sweat, and you need to replenish your body's water supply often. If your coach doesn't bring water to games and practices, get your parents to suggest that water be provided -- and that your coach should schedule breaks for drinking it. :: Am I a good loser?

Sometimes, being a good sport is the hardest part of playing competitively. Losing hurts! But any professional ballplayer will tell you that learning to accept the loss and go on is a major part of any game. In every contest, someone has to lose. It isn't easy, but professional athletes learn to lose gracefully. You should too. :: Do I follow a well-balanced diet?

Eating healthy meals from the four food groups -- 1) milk and dairy products 2) meat, poultry, fish, beans and eggs 3) fruits and vegetables 4) breads and cereals -- gives your body the energy it needs to run, jump and play. Eating well is especially important if you do a very demanding activity such as wrestling or ballet dancing. :: Do I know basic first aid?

Anyone who plays sports should know what to do if someone gets hurt. If you're not sure, ask your parents to get a first-aid handbook for your home. Read it with them so your whole family will be prepared for an emergency if it happens.

Did you answer "Yes" to each question? If you did, you're doing a good job at defending yourself when you play sports. If you answered "No" to any of the questions, it's time to get on guard and protect yourself better. Tips for Parents

The quiz above is adapted from the National PTA's sports safety tips, published in the organization's Safety Planning Kit for 1987's Child Safety and Protection Month. The kit is designed to guide local PTA and other groups in planning safety programs for children and teen-agers. PTA member groups can purchase the kits -- which also address safety concerns about babysitting, emotional abuse, emergency preparedness, bicycle, rollerskate and skateboard safety, and stress -- for $2.50. The cost is $10 for the general public. Supplies are limited. Contact the Program Department/Safety Center, National PTA, 700 N. Rush St., Chicago, Ill. 60611, or call (312) 787-0977 for order forms and information.Catherine O'Neill is a free-lance children's writer in Baltimore.