As part of working on Dead Bunny’s Guide to Algebra, I’m trying to develop tips and tricks for handling a variety of situations. While it’s helpful to understand why these work, sometimes it’s much more useful to know the tips themselves.
This week,I was working on tips for working with integers, since those often stump my students. I’m asking them for feedback, and I’m asking you to tell me what you think, too.
- When adding numbers with the same sign, add the numbers together and put the sign in front of the answer.
- When adding number with different signs, subtract the numbers and put the sign of the larger number in front of the answer.
- When subtracting integers with the same sign, subtract the integers and put the sign of the larger integer in front of the answer.
- When subtracting integers with different signs, add the integers together and put the sign of the larger number in front of the answer.
Multiplying and Dividing Integers
- When the numbers being multiplied or divided have the same sign, the answer is positive.
- When the numbers being multiplied or divided have different signs, the answer is negative.
I don’t understand what you mean by “…combine the symbols in the middle, subtract/add them and…” How do you combine, subtract, or add symbols? You may want to clarify the wording.
I tell my students—or at least, the ones who are easily confused—to change all subtractions to additions (adding the opposite number), and then follow the relevant addition rule. For some psychological reason, addition is easier.
Comment by Denise — January 24, 2008 @ 10:00 am |
I’ve tried to explain to students to change all subtraction problems over to addition, and even with visually showing to them what’s going on, I seem to confuse them more.
I suspect with the visual representation in the blog and the book, part of the statement is clearer, but I can definitely see where I’ve got a pronoun-antecedent problem going. (But that’s why I like to bounce things off people!)
Comment by kirylin — January 26, 2008 @ 9:04 pm |