Teacher2Teacher |
Q&A #421 |
From: Gail
(for Teacher2Teacher Service)
Date: Jul 16, 1998 at 00:32:38
Subject: Re: Teaching fraction addition
Have you ever had students make fractions strips, and then use them to compare fractional amounts? In case you haven't here is a quick set of directions. (You could also buy these materials, but if a child makes them, that is part of the learning.) Cut a set of strips that are all the same size. You can do that by using lined paper and cutting them so that the lines are running vertically through the strips ( up and down). If you make each strip 24 lines long, that will make some of the folding easier, too. Now, label the first strip "one whole". It will be worth one. Take another strip, fold it into two equal pieces, and label each one "one half" (you can also use the fraction 1/2, to help your students link the word and the symbol). Take another strip, and fold it into four equal pieces (to be labeled fourths). There is more than one way to do these folds. To make it easier to compare them later, making the folds vertically, so the segments are all in line, is best. It is a good idea to let your students see how many different ways they can make these folds to create "equal" pieces, though. Continue to make all the fraction pieces from halves to twelfths. Some will be more difficult to make than others. Working through the activity will help your students see the relationships between the fractions though. Resist the temptation to do it for them so the materials look neat... When you are done, you can use these strips to compare fractions to see how many of one strip make the same sized piece as another strip. You can also compare to see which pieces are larger, or smaller than other pieces, for example, 12 is smaller than 5/8 and 8/12. Finally, you can use them to add and subtract fractions. Suppose you want to add three fourths and one half. You find the one half strip, and the fourths strip. Lay them side by side to notice that one half is the same as two fourths. Now lay them one after the other, like a long train. You have the half, which is the same as two fourths, and the three fourths. That is five fourths all together. It is longer that the one whole strip, so it must be worth more than one. you can compare to find out how much longer than one it is. If the fraction were 4 sixths and 3 fourths, you could still add them. Put them like a train, and note the length. Find a strip that compares with both the sixths and the fourths ( twelfths work) Change the names of the two fractions into twelfth, by comparing. Then figure out by substituting how many twelfths you have... -Gail, for the Teacher2Teacher service
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