Q: Thin, blade-like runners will increase speed on icy surfaces. Sleds that slide along one large base without runners are better for deep snow, since they distribute the rider's weight more evenly and reduce sinking. Sleds with wide runners are somewhere in between. Most casual sledders just use one sled for all terrain, but if you're buying your first sled, pick one that will work on the hills you expect to be trying. Sleds with metal runners or sliding surfaces tend to be faster than wooden or plastic sleds, since they create less friction. Metal sleds are usually more expensive, though. Sleds with runners and steering mechanisms are the safest type of sled for children. This may not hold true for high speed sledding. Most people don't think of sledding as a dangerous sport, but serious or fatal sledding injuries do occur regularly. Wearing a helmet is an excellent idea for children, as well as for adults who are sledding down steep, tall, icy, or obstacle-laden slopes. Thick winter clothing usually gives enough protection for the rest of the body. Find a hill completely covered by snow or ice, since dry patches can stop your sled. Never sled on a hill covered in obstacles, or one that ends in a parking lot, a street, or a body of water. If there are other people around, choose a side of the hill where you won't run into them. Stay seated while the sled is moving, and face forward at all times. Do not face backwards, lie down face-first, or try to spin the sled, as this can make a crash much riskier. Some sleds are designed for the rider to lie face-first, but these should only be used in specially prepared lanes at winter resorts, or by experienced sledders. You can steer by leaning in the direction you want to turn, or by putting your foot out into the snow on that side. To slow down or stop, put both feet out into the snow. Larger sleds and sleds with runners often have ropes you can pull to turn the sled, or more rarely a steering wheel or other unusual mechanism. If you need to turn very suddenly or at high speed, use multiple steering techniques (for instance, lean and put out a boot at the same time). Tube-shaped and disc-shaped sleds can be very difficult to steer, and should only be used on wide, open areas with no obstacles or preferably in special lanes in "tubing parks" and other winter recreation areas. If you lose control and the sled is going too fast for you to stop, cover your face and head with your arms, then roll out the side of the sled.
A: Choose a sled for ice or for snow. Wear a helmet if necessary. Choose a safe hill. Sit facing forward. Learn to steer your sled. Bail out if you lose control.

Q: Studies show that brushing can prevent gingivitis. Effective brushing should not only reach in between teeth to remove plaque, but also massage the gums to stimulate micro-circulation in that area. The best technique for brushing your teeth is the modified Bass Method. Orient your brush in such a way that its head is tilted at a 45-degree angle towards the gum line. This allows the bristles to clean 1 mm below the gum line. Use small, vibratory, circular strokes to remove plaque. After about 20 strokes, do a sweeping motion towards the biting surface of your teeth. For the biting surfaces, do a back and forth brushing stroke. Repeat these steps for all of your teeth. Flossing helps to remove plaque along the margins of your gums. This saves the gums from getting irritated by bacteria present in plaque. Floss first, since flossing brings the plaque stuck between the teeth out, and then you brush it away. Get an elbow length piece of dental floss and wrap each end around your middle fingers. Leave at least an inch of floss between your fingers to work with. With the help of your index finger, gently slide the floss in between your teeth, starting at the back. Allow the floss to hug the surface of your tooth and gently slide down to the gum line. Then, drag the floss against the surface of your tooth. Do not force the floss in between your teeth as this could damage your gums and cause bleeding. Repeat the same steps between all of your teeth. Dissolve 9 teaspoons of salt in three cups of warm water. Rinse for 30 seconds, then spit out. Do this twice a day. Rinsing with salt water is an effective way to reduce the bacteria in your mouth. The bacteria present in plaque causes irritation of your gums. Salt rinses create a diffusion gradient inside the mouth. This means that it causes the bacteria to become dehydrated and die. Those that smoke are more likely to get gum disease, as smoking is very hard on the gums and bone, causing bone loss, which subsequently is more difficult to keep clean. The habit can give you a variety of gum problems, including sensitive gums, bleeding gums, or painful sores on the gums.
A:
Brush your teeth at least twice a day. Floss before brushing. Use saline rinses. Quit smoking.