So they can open doors of opportunity for their students.
Because they are a-door-able.
A door to door salesman!
Adobe Wan Kenobi
Gloves. Just kidding he couldn't open it to find out
A student used to give his teacher some raisins everyday. He kept giving them for 3 months straight. Then one day he did not give raisins to his teacher. And his teacher asked him "Where are the raisins today?", and the boy said "My rabbit died."
Mister bus
Student: "By staying home"
Teacher: Why are you Late Today? Student: Because of sign down the road. Teacher: What does a sign have to do with your being late? Student: The sign said, "School Ahead, Go Slow!"
That is impossible. Opportunity doesn’t come knocking twice!