At one point in the semester, I had these written out on my dry erase board. I never saw anyone use them, so I decided to erase them when I cleaned my board. The next day, I had several students questioning me about where the rules had gone. So, I rewrote them on the board. A week or two later, my computer and Smart Board decided to stop working. No Smart Board means I have to use the dry erase board. So, I ended up erasing the rules again. And, again, I heard from several students who wanted to know where the rules had gone.

They've been erased for a while now with no more complaints, but we're getting ready to start graphing using a t-chart. So, I wanted to create a permanent place in my classroom to post a short reminder of the rules. It is my goal that by the end of the year all of my students will know these by heart. But, until then, I want them to have a place to look when they can't remember instead of just guessing.

Here are the posters I created.

Integer Operations Posters |

Download files here.

but if there are three negatives multiplied together ....they have the same sign but the answer is not positive. My sixth graders arrived saying that if the signs were the same the answer needed to be positive. We did some hands on with a 'sea of zero' and discovered it wasn't true. Maybe an asterisk is needed on the multiply/divide posters

ReplyDeleteI use even and odds in my definition of multiplying integers. 0 or 2 negatives make a positive, one negative makes a negative. Give them a series of problems with (2)(-2) and (-2)(-2) and (-2)(-2)(-2), and have them figure out the pattern.

ReplyDeleteI also explain it in lecture with a red/yellow counter chip "coin" that we have for integer ops. Negative means "opposite of" and is represented on the coin by a flip from yellow to red, and so the opposite of the opposite is a flip of a flip, back to yellow. Flipping the coin from positive yellow to negative red to positive yellow, etc, gets them picking up on those patterns that will be so useful once they hit imaginary numbers!!!