Negative Numbers

Benjamin has gotten up to adding and subtracting positive and negative numbers. Some of it makes sense, but subtracting a negative has been a bear to wrap our minds around. If zero is nothing, then how can you take away even less than nothing? I was really struggling to find a real life example. Drew came up with a great one and a friend tied it into English for me. I'll be going over this with Ben today - we'll see if he sees it as clearly as I'm beginning to.

Drew's thought - He compared it to heating and air conditioning. Heating is positive numbers and cooling is negative numbers. Turning either the furnace or the AC up (more power) is adding and turning them down (less power) is subtracting. So, turning up the heat is like adding a positive and it gets warmer. Turning down the heat is like subtracting a positive and it gets cooler. Turning up the air is like adding a negative and it gets cooler. Here's the tricky one: turning down the air is subtracting a negative and it gets warmer. I can see this organized on a chart with up & down on the sides and heat & AC on the top (like Mendel's sweet pea genetics), but I don't know how to reproduce it here.

My friend reminded me that, just as in English, two negatives make a positive.

A bunch of other friends sent me other examples that I haven't had time to look closely at yet, but we'll tackle them this afternoon.

SDG!