Doing math questions with all sorts of negative signs is the bane of many a math student’s existence. This is how I teach integers once students need to move beyond manipulative and be able to do these questions as mental math.
CLICK on the video on the right for my mini-lesson or, READ ON to find out more!
John Mighton
I had the amazing opportunity to attend a workshop put on by John Mighton when he came to Toronto one year. (Remember the movie, “Good Will Hunting”? He was the Math Expert Advisor for that movie….and also played the professor’s assistant. How cool!).
Anyway, I asked him how he teaches students how to do questions such as:
– 3 – 4=
– 4 + 5 =
-5 – 6 =
You get the picture.
I now use what he said to help me teach integers all the time. It has helped even my grade 11 students who never felt like they fully understood the concept!
Treat it like Money
Most kids are pretty familiar with basic money exchange at this point and it’s a great and intuitive analogy/tool to use to teach integer concepts.
What do I mean? Take the following question on the right:
The “story” would go like this:
“One day you wake up with $3 in your pocket (or wallet). Unfortunately, you get to school and a friend says you OWE them $7 more.”
Good Day or Bad Day?
Before I teach them how to deal with the numbers, we learn to “read” each question as a story and we decide if, at the end of the day, it is a “good day” (they end the day with money in their wallet) or a “bad day” (they end the day in debt).
If it is a good day, the final answer will be positive, if it is a bad day, it would be negative.
I put a few more questions like this on the board and we just practice this skill until all students are comfortable with it.
Now for the Integer Answer
Once students get to this part, their preexisting knowledge of money kicks in and takes over and the math suddenly becomes a lot more intuitive.
Do a few more examples with them, with increasingly large integer values. This increases their mastery of the skill and also increases their confidence. Something about being able to do math with huge numbers is so confidence-building for a student! (Think $100 – $112 i.e 100-112, which they probably can now do in their heads!).
Want More Examples?
Hope this helps your students. I’d love to hear about your experiences if you tried this out, or if you have any other tips and tricks you use to teach this concept.
If you’d like to learn more about John Mighton, he has created a whole line of math resources called “JUMP Math”.