Check out this kid’s explanation for why you end up with “+3x” from “-(-3x)”:

“You have -3x, so that’s three negatives, and then you have this other negative and that makes four…”

You can find this explanation at around 3:33 in the video below:

Exponents strike again!

(Or, maybe I misunderstood the kid’s explanation in the video? Lemme know if I did, please!)

Thanks to Jonathan for the submission.

Camera 360


I think the temptation I have is to call this a “careless” mistake and urge more practice. Let’s probe deeper.

1. What does this kid know and understand about exponents?

2. What’s the fastest way to help?

3. What makes this mistake so tempting?

Thanks to Sadie Estrella for the awesome addition to our ever-mounting pile of exponents mistakes.