
Re: Simplifying Algebraic Expressions with Subtracted Expressions
Posted:
Nov 16, 2013 2:52 PM



On Nov 15, 2013, at 11:06 PM, Pam <Pamkgm@hotmail.com> wrote:
> Exactly. This is what students studying the Singapore curriculum are prepared for. And note all that convenient space for each problem  plenty of room for drawing some bar diagrams!
But the solutions posted don't use bars. And if shading is the only trick in the student's bag, they will barely be prepared to fill in their name on those exams. Those are actually tougher than the actual PSLE. I guess the top schools leave nothing to chance.
On Nov 15, 2013, at 11:06 PM, Pam <Pamkgm@hotmail.com> wrote:
> You should spend some time with bar diagrams  you just might discover what a powerful tool they are for promoting algebraic thinking, for children in the prealgebra stage. In some ways, it is what the Singapore textbooks are all about  developing a more and more sophisticated and flexible ability to use bar diagrams to solve more and more sophisticated problems. Problems that are not accessible to 5th and 6th grade students learning from other curricula.
I have studied them. I even pointed out to you how they are supposed to be used. There is even talk of removing them altogether from the curriculum, because it hurts the kids in algebra. But that isn't my position. My position is to stop using them like a gimmick. There are no gimmicks in mathematics. If you use them as a diagram they promote algebraic reasoning. If you use them to count they promote nothing beyond 3rd grade fractions. Like I said, if I did what you did in geometry you would see the difference. Maybe at some point you will see it in arithmetic as well.
All you have to do is stop the arbitrary divisions, markings and counting, and let arithmetic reasoning take its course.
Bob Hansen

