In this lesson students review how to find the distance between 2 points, vertically and horizontally, on the coordinate axes. Students are then introduced to the concept of finding the distance between 2 points that are diagonal from one another. Students are taught to connect the 2 given points by a line segment. This line segment then serves as the hypotenuse in a right triangle. Students use the Pythagorean Theorem to find the length of the hypotenuse. Using the Pythagorean Thm. is a prerequisite skill for this lesson. There are several example problems as well as practice problems (with solutions).