Over the past two days, both the Sec 4 and Sec 5 students have been reviewing integers. Yesterday, we learned how to add integers and today, we spent a good amount of time discussing how subtract positive and negative integers.
About 60% of the students were able to master both concepts fairly well by the end of class. I have to say that’s pretty good, considering our periods are only 50 minutes! I used dual coloured foam chips; we use red for negative and white for positive.
I model how I subtract or add on the Smartboard with this convenient website from McGraw Hill. I walk around and ask students to do it themselves. Some of them get confused at first because they’re reluctant to participate, but I model how I count – touching a “zero sum” with two fingers and saying “zero” – with my hands. Once they start doing it, the gears start turing and they get their “aha” moments.
Of course, adding integers with chips is easy.
But how the heck do you subtract 7 from -2? You start with two red chips and then …?
I won’t go into a lengthy explanation. This video below explains it pretty well:
It just felt great to see the kids really eating up the math!
At the end of the day, I dug around YouTube to see if I could spice up my lesson a bit and came across this lovely gem, PBS Math Club! They’re not cheesy or lame; on the contrary, the series is professionally done and the actors and actresses are pretty hip young teenagers who can hold their own. Check it out! There’s a pretty good definitely of adding and subtracting positive and negative, using an analogy of how much good and evil is happening in the city of Gotham!
I will have to play this tomorrow in class before we practice our skills with Integer Wars. The kids are really gonna get a kick out of this!
*It’s especially important for Second Language Learners to watch videos with closed captioning where possible. I myself watched a lot of Frasier as a teenager and learned a lot of good words that way!