Discovering Negative Numbers

Today I had a three hour Math Boot Camp where I reviewed basics and exposed new to our school students to math topics that our current students have already been taught.  I do not expect them to grasp these topics in one day.  But, it is great exposure for them and I get to see where they are mathematically so I can more accurately plan for these students this fall.  Again, this is exposure, not a full blown lesson.

One of the main topics today was the discussion of negative numbers.  Kids have such a hard time with this because they are taught so many “rules”.  Man, I hate rules kids have to memorize for math.  Today several kids even told me some of the rules they had learned, but didn’t know what they meant and could not apply them.  I actually prefer this to kids that just apply these rules because I can wipe the slate clean and start fresh with them.

I started with the idea of a negative number, showed them patterns so they could discover the answer, and then moved to a number line.  I also frequently referred back to the “concept” of a negative number often and pull finances in at every opportunity.  I mean seriously, what kid doesn’t understand simple money spending?  (As in, I want this awesome xbox game that cost $50, but I only have $30.  My Mom buys it for me and now I owe her $20, thus -20).

To introduce them to the idea of negative numbers, I asked them to represent (on a whiteboard) numbers for the scenarios that I gave them.  You received $45, 15 degrees below zero, you owe 27 dollars and 62 cents (decimals too), the depth of the titanic and the height of skydivers.  I told them they have been using negative numbers for a long time and didn’t even know it.

Then I moved on to patterns. The patterns I used were very simple and kids even laughed when we went through them.  This stuff is TOO easy and they loved that.  They got to see negative numbers come out and they were excited that they discovered the pattern.

  • 4 – 1 =
  • 4 – 2 =
  • 4 – 3 =
  • 4 – 4 =
  • 4 – 5 =
  • 4 – 6 =

After this I modeled subtraction on the number line, always bringing in parallels to money.  Then, I moved on to more patterns.

  • 4 – 2 =
  • 4 – 1 =
  • 4 – 0 =
  • 4 – (-1) =
  • 4 – (-2) =
  • 4 – (-3)=

This was a brief introduction today.  I am going to add more discovery and the need for working with numbers like -4 – 5  =  for an in-class lesson.  I didn’t hit them with multiplication and division of negative numbers as I didn’t want to confuse them.

After all of our pattern work today, one kid even said, “My IQ just doubled today.”  Did I mention how much I LOVE 6th graders?

I hate saying, “Subtraction of a negative”.  Or “minus” a negative for 4 – (-3).  What does everyone else say?  And how are you all teaching negative numbers?  I would love more ideas and discussion.