My teacher said it was rise over run but i don't understand.

Here u go fren this is what rise over run means

Ok so from your point you rise then run the number told. So if your slope was 8 over 3 (8/3) you would rise 8 spots then go over 3. Rise is in go up (or down depending if its a negative or a positive) and run means go to the right or left (again depending if it's a positive or negative). In that first example your slope is 1/1. And lets say your point is (4,0) go up 1 and to the right 1 and graph that point, so your next point would be (5,1). To make sure you got it right. Remember if your slope is a negative you either go down and to the right or up to the left. To check your answer from left to right if the line is increasing it's a + and from left to right it decreases it is a -
Sorry about this big paragraph but I hope this helps :)

Use a calculator basically