How to Use Fraction Bars to Find the Sum or Difference

Adding Common Denominators

• 1

  Add 1/4 and 2/4. Find the fraction bar that represents one-fourth, a bar with four sections, one of which is shaded.

• 2

  Find the fraction bar that represents two-fourths, a bar with four sections, two of which are shaded.

• 3

  Place the 2/4 fraction bar over the 1/4 fraction bar so that the shaded sections align horizontally.

• 4

  Count the number of shaded sections to find the sum -- 1/4 + 2/4 = 3/4. Notice that when lined up, the shaded portions of the two fraction bars are even with the third section of the blank fraction bar guide.

Subtracting Common Denominators

• 5

  Calculate 7/10 - 3/10. Find the fraction bar that depicts 7/10, a card with 10 sections, seven of which are shaded.

• 6

  Cross off three of those shaded sections with a dry-erase marker.

• 7

  Count the remaining sections to find the difference -- 7/10 -- 3/10 = 4/10.

Adding Different Denominators

• 8

  Add 1/2 and 1/5. Find the fraction bar that represents 1/2, a bar with two sections, one of which is shaded. Find the fraction bar that represents 1/5, a bar with five sections, one of which is shaded.

• 9

  Lay them on the table side by side.

• 10

  Find a fraction bar of one color that has the same shaded area as the 1/2 bar. Place this bar on the table, below the 1/2 fraction bar.

• 11

  Find a fraction bar of the same color that has a shaded section equal to the 1/5 bar. Place this bar on the table below the 1/5 fraction bar. It may take several tries to find bars of the same color that equal both fractions. For beginners, you can skip right to using a yellow bar or a tenth fraction bar.

• 12

  Compare the second set of fraction bars to the first set. Notice that the colored sections of the second set have the same shaded areas as the first set. This means they are equivalent fractions -- 5/10 = 1/2 and 2/10 = 1/5. Since the fraction bars are the same color, that means they have a common denominator.

• 13

  Count the shaded sections from the second set, or same colored, fraction bars for the sum -- 1/2 + 1/5 = 5/10 + 2/10 = 7/10.

Subtracting Different Denominators

• 14

  Calculate 1/2 - 1/3. Find a fraction bar with one out two sections shaded and a fraction bar with one out of three sections shaded.

• 15

  Lay the bars on the table horizontally and parallel to each other. Notice that the shaded area of the second bar is smaller than the shaded area of the first.

• 16

  Find a fraction bar with the same shaded area as the difference between the first two bars. You should have picked a red bar, or a sixths fraction bar and after counting the shaded sections, you can see that one out of those six sections equals the difference between the 1/2 and 1/3 fraction bars.