
Re: Simplifying Algebraic Expressions with Subtracted Expressions
Posted:
Nov 15, 2013 10:54 AM


I assume you are equating "graphic" with "symbolic"? Can you elaborate?
Bob Hansen
On Nov 15, 2013, at 10:02 AM, Joe Niederberger <niederberger@comcast.net> wrote:
> Pam says: >> Yes, 5th grade, and not particularly hard through the use of the bar diagrams that students studying from the Singapore textbooks are practiced with. They would draw a horizontal rectangular bar, divide it into 5 equal parts, lightly shade 3, divide each of the remaining 2 parts in half (as well as the original 3 so as to continue to have equal portions). By shading 1/4 of the "afternoon tarts" (1/10 of the whole bar), and shading an equal portion of the "morning tarts", what is left of the morning tarts is equal to 200. Since there are 5 parts, each part is equal to 40. > > Nice description. I would say that certainly qualifies as "formal manipulation" as in Lou's definition of algebra: > > "it's the conscious formal, symbolic representation of an unknown, together with its subsequent manipulation, that turns the solution into an algebraic one." > ( Lou Talman) > > Cheers, > Joe N

