One of my young adult children posed the following question: “When I’m reading my credit card statements, do positive numbers represent money that I have, or money that I owe?” Then I realized that in finances, a negative number indicates a credit. Do they teach kids these things in schools? No! One of the reasons to unschool is that children get real life application of math facts.
When my kids were learning about boosting car batteries, about the same time that they were using red and black tiles to represent integers, (where red is the negative integer and black is the positive integer) I showed them how to boost the car battery with the red clamp connected to the negative post (which I’m sure is negative because in math and finances, red is always negative) and the black clamp to the positive post. The result was BOOM! You would think the math world and the electronics world would collaborate a tiny bit and then teach the kids a uniform color!