The stratosphere (/ËstrÃ¦tÉËsfÉªÉr, -toÊ-/) is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. About 20% of the atmosphere's mass is contained in the stratosphere.
The chainsaw is a highly effective and efficient tree and branch cutting power tool. It works with an engine, referred to as a power head; powering a metal chain, driven by a centrifugal clutch, with a chain moving around a groove in the guide bar at fast speeds.
seesaw A seesaw is a piece of playground equipment made of a board balanced on a center support. To play on a seesaw, you sit on one end with a friend on the other end, moving up and down. You might also call a seesaw a teeter-totter â they are common in parks and on school playgrounds. When you sit on a seesaw, with your friend on the opposite side, each of you takes turns pushing up off the ground.