>> reporter: professional skateboarder billy rohan is the coach. was running a popular after school program when the principal took notice. >> and so, i asked billy, would you be interested in doing this as a gym class, and he jumped at the idea. >> i put together a curriculum and we started the class. it was a big success. >> reporter: most adults probably look at skateboarding as a rather hazardous sport. but billy says with the right emphasis on safety it's really not. >> one of the biggest myths of skateboarding is how dangerous it is. it's actually way less dangerous than most sports. like the most common injuries are sprained ankles and sprained wrists. so we try to warm them up enough where that doesn't happen. >> reporter: so class begins with stretching. >> left leg. one two -- i can't hear you. three, four. >> reporter: billy also makes sure students always wear their safety gear. drills are next. and for the last 20 minutes of class they free-skate. >> free skate is where i see kids progress the most. the idea is you copycat each other a