Negative Numbers are Positively Interesting.

A math conversation with Tara

Tara: Is 3 minus 6 negative 3?

Me: When did you start learning negative numbers?

Tara: Oh, we din’t. Just some older kids in Art class were talking about it.

Me: Yes, 3 minus 6 is negative 3. Negative means as though it’s owed. So, if you have $3, and you need to pay me $6, you can pay me the $3, and you still owe $3. So, you are $3 in deficit(negative $3). 

A new way of subtracting

Today I won the bet on snow day. I bet that it would snow, and we’d go sledding (I always vote for that). The kids were home. After sledding and soup, they were helping me test Second Grade Math. Its my way of getting them to practice math while they also find bugs for me to fix. We worked on some tough subtraction problems using borrow.

Borrow

But, then she started asking –

Tara: so, 6 minus 7 would be negative 1.

Me: Yes, But, since we borrow the 10, we end up with 10 minus 1, that’s 9.

Tara: In the tens, 0 minus 6 would be negative six.

Me: Yes. Since it’s tens, that’s actually negative sixty. That gives me a thought. We can solve this another way….

negativenumbers

Tara: I want to do more like that. That’s more fun. 

After doing a few…

Tara: Its easier this way.

Me: You better practice borrow too. It’s needed for school.

Tara seemed more interested in trying unusual things with numbers – exploring and seeing how things go – far more than she is, when I am trying to teach her a specific topic. From our last conversation about math (on patterns), she has all her second grade class computing fibonacci sequences with different starting numbers (she wouldn’t accept that fibonacci must start with 0,1) into the 1000s. It was a wonderful way for all of them to practice addition. I wonder where this conversation will end up.

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