The Doorway To A Clearer Explanation

(We are in physics class talking about motion. There is a window on the left wall and the door is on the right wall. We are on the second floor.)

Teacher: “Okay, so when I point to your left, that will represent negative direction, and the right will represent positive.”

Student: “Because if you go to the right out the door, everything will be fine, but if you go to the left out the window, you’ll die.”