Name: Angela
Elementary level
I'm a teacher.


1. represent multiplication of fractions via an area model

2. describe why, not just how, to round decimals

Thank You!

Hi Angela,

If your students have calculated the area of a rectangle with integer sides by multiplying the integers then you can use this concept to represent the multiplication of fractions.

Suppose that you want to multiply  1/2 and  3/4. Draw a unit square and divide it in half in one direction and in quarters in the other. The region shaded in purple below has an area represented by  1/2 x 3/4

In this construction you divided the unit square into eight, equal sized rectangles so each rectangle represents one-eighth on the unit square. Hence the purple region is three-eights of the unit square so that  1/2 x 3/4 = 3/8

For your second question one example that immediately come to mind is with money. Suppose that you purchased something for $28.95 and you have to pay 7% tax. Then the tax is $28.95 x 0.07 = $2.0265. Since we don't have coins worth less than $0.01 we round the tax to $2.03.

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