In this Youtube video from TheDouceHouse, he discusses 2 different ways of measuring arc length, by degrees and by distance such as inches. He also show 3 different example problems, problems you will likely see in class, on how to find arc length using a proportion. The three different example have you find arc length, central angle, and radius of circles.
This Youtube video lesson from MrPilarski discusses how to find the length of an arc. First, the arc length theorem is reviewed and explained. An example of find the length of a major arc is modeled. The given information is the measure of the related minor arc and the radius of the circle.