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 Discussion: All Topics Topic: Fractions...Subtracting mixed numbers

 Post a new topic to the General Discussion in Math 6 for Subtracting fractions discussion

 Subject: Subtracting mixed numbers Author: Cathy Date: Nov 10 2003
My students call this the "Bubble Gum Method." In this method the minuend is the
amount of bubble gum you have, the subtrahend is the amount you want to share
with a friend. The difference is the amount you have left. For example 6 1/3 - 2
5/6. First find the common denominator. Now begin the story,"You have 6 and 2/6
packs of gum in your pocket your friend Cory wants you to share, she wants two
and 5/6 packs. How can you share with Cory and what will you have left?
Questions that help lead the students to understanding the problem. How many
pieces of gum do you think are in each pack of gum and why? 6, because you have
6ths. What do you have to do to give Cory her portion of the gum? Give her 2
pieces and then open a new pack and and give her three more pieces. Then hand
her 2 unopened packs. What do you have left? 3 unopened packs and 3 pieces or  3
packs and 3 out of 6 pieces, 3 and 3/6 equals 3 1/2 packs. By relating fractions
to something with which the students are familar seems to make understanding
easier. If the fractions are large it can be bags of candy, but the idea is the
same. From there you can relate the steps to the traditional algorithm    . Hope
this helps.