I suppose as a kid, it's tough to focus on learning something new when your dad tells you that the entire universe might be erased by a minus sign. We'd pretty much exhausted the positive integer subtraction worksheets, but had a high-motivation goal on the table involving another iPod download here, so something had to fill the gap in the space-time continuum... I figured it wouldn't be a big deal to toss out one of the introductory subtraction pages on negative numbers because I had the time to introduce the concept and work through a few examples. Unfortunately, as far as my young charge was concerned, negative numbers might as well have come from Mars. Or worse. Much, much worse.
"Negative numbers? How do you have minus something?"
"It's not like having something, it's more like owing somebody something... Pretend I give you ten M&Ms, and you say you'll give me ten back later. It's kind of like you have negative M&Ms because you have to give them to me later."
"But I have ten M&Ms because you just gave them to me."
"No, pretend you ate them."
Pause of imminent doom.
"No I didn't. Here, I'm pretend giving them back. I don't want negative M&Ms". The more I talked, the more negative numbers sounded not just odd, but down right scary. Numbers that can cancel out other numbers? Sudden risk to the global candy supply? By the time I exposed that Bank of America might, without asking, take money out of your bank account for overdraft fees, my daughter was pretty sure the world was coming to an end. I'm fairly certain the Birds and the Bees conversation is going to be feel like a walk in the park after all this. For half an hour we danced around the growing risk of explosion from the matter-antimatter annihilation of the numbers I created. Micro-black holes at the Large Hadron Collider had nothing on me here. Before we plunged across the event horizon into a stretchy existence shredding demise, I gave up talking and my old friend, the trusty number line, pulled us back to safety. In these situations, you don't know you're on solid ground until you hear, "Oh that's it? That's easy!" in your ears. Thank you, Mr. Number Line... The world is safe from antimatter M&Ms and overdraft charges for now. And, thinking about it, maybe I'll just wait a while more on the Birds and the Bees, too. New Number Line worksheets are posted here: Introducing Addition with the Number LineIntroducing Subtraction with the Number LineIntroducing Negative Numbers with the Number Line