procedure
A set of steps to do something in the right order.
A procedure is a set of steps followed in a specific order to accomplish something correctly and safely. When a science teacher explains the procedure for a chemistry experiment, she's telling you exactly what to do first, second, and third so nobody gets hurt and the experiment works. When a doctor performs a medical procedure, she follows carefully designed steps that other doctors have proven effective.
Procedures exist because someone figured out the best way to do something important, then wrote it down so others could do it the same way. Fire drills follow a procedure: when the alarm sounds, students line up, walk to their designated spot, and teachers take attendance. This procedure works because everyone knows their role and follows the same steps every time.
Some procedures are simple, like the procedure for checking out a library book. Others are complex, like the procedure astronauts follow before launching into space. Even something as ordinary as making pancakes has a procedure: mix ingredients in the right order, heat the pan to the right temperature, and flip at the right moment. Following procedures carefully means you're more likely to get the result you want, whether that's fluffy pancakes or a successful rocket launch.