The Four-Stroke Gas Engine

A four-stroke engine is a machine. It helps a vehicle move. It was invented in the late 1800s, but it is still common in cars today. The four-stroke engine works by burning fuel, which creates energy to make the engine go. The engine does four things to work properly. First, it takes in air and fuel. Then it squishes them together. It makes them explode with a spark. Then the engine pushes out the waste gasses. This process keeps repeating, and it helps the engine run and the vehicle move. Four-stroke engines are the most common engine for automobiles, trucks, trains, small airplanes, and motorcycles. However, the exhaust from these engines contains a great deal of greenhouse gasses as well as other forms of air pollution. Therefore, the use of four-stroke engines in cars will soon be phased out in many parts of the country.

INSTRUCTIONS: Match each stroke with its description.

a. it makes the air and fuel explode with a spark
b. it pushes out the waste gasses
c. it takes in air and fuel
d. it squishes the air and fuel together