Calvin and Hobbes by Bill Watterson for September 19, 1990
Mom: How's the math lesson going? Dad: Pretty good. I think Calvin sees the idea now. I took pennies and showed how adding and subtracting them changed how much money he had. It's not so abstract that way. Mom: Good. Maybe he'll do better in class now. Dad: I think he will. He was having fun with it by the end. Calvin: Now give me another five cents and let's see what I have! Hobbes: Wait a minute.