needed to match changes in the steepness of the run. This looks more like a single series of S's than turns followed by straight sections. Stemming The oldest and still common type of turn on skis is the stem, angling the tail of the ski off to the side, while the tips remain close together. In doing so, the snow resists passage of the stemmed ski, creating a force that retards downhill speed and sustains a turn in the opposite direction. When both skis are stemmed, there is no net turning force, only retardation of downhill speed. Carving Carving is based on the shape of the ski itself; when the ski is rotated onto its edge, the pattern cut into its side causes it to bend into an arc. The contact between the arc of the ski edges and the snow naturally causes the ski to tend to move along that arc, changing the skiers direction of motion. Checking This is an advanced form of speed control by increasing the pressure on one inside edge (for example the right ski), then releasing the pressure and shifting immediately to increasing the other inside edge (the left ski). Then repeat if necessary. Each increased pressure slows the speed. Alternating right and left allows the skis to remain parallel and point ahead without turning. The increase and release sequence results in the up and down motions of the upper body. Some skiers go down the top of moguls and control the speed by checking at the tops. This is how they can practically go straight down the fall line without gaining speed. Snowplough turn The snowplough turn is the simplest form of turning and is usually learned by beginners. To perform the snowplough turn one must be in the snowplough position while going down the ski slope. While doing this they apply more pressure to the inside of the opposite foot of which the direction they would like to turn. This type of turn allows the skier to keep a controlled speed and introduces the idea of turning across the fall line. Equipment Skis Modern alpine skis are shaped to enable carve turning, and have evolved significantly since the 1980s, with variants including powder skis, freestyle skis, all-mountain skis, and children's skis. Powder skis are usually used when there is a large amount of fresh snow; the shape of a powder ski is