# Analogies and Directed Numbers

Directed Numbers – positive and negative numbers – is abstract, particularly the negative thing.  Bank statements aside, it is rare for us to see negative numbers. We don’t even have sub-zero temperatures here in Sydney; not in our waking moments anyway.

While I’ve taught my year 7 class about ‘two negatives make a positive”, this remains an elusive concept to understand.  At least they remembered what I said.

Being an ESL-speaker myself, I spend a fair amount of time with literacy within the context of maths. Revising Directed Numbers today, we went through words that were associated with Positive and Negative. One of the most useful ones was ‘not’ for negative.

not down – up

not left – right

not negative – positive; i.e. minus negative is a plus (positive)

On the last period on a warm Friday afternoon, cheerful “I get it” from students is like a cooling G&T or glass of iced water (non-alcoholic option).

I guess this post is more about my teaching than learning.

I’d like to say the ‘not’ thing was completely random. The truth is, I used ‘not’ a lot in my computer programming days. If you think of computers as a collection of switches (which is a very simple but apt analogy), all you’ve got is on and not on (off). I still use ‘not’ in my SQLs. Sometimes it’s a lot easier to say NOT (A or B), particularly when you want the rest of the 24 letters, or something like that. Example is interpreted as Not A AND Not B; the not applies to the OR as well. But this is going into Boolean Algebra…oops, algebra again.