Adding and Subtracting Fractions with Unlike Denominators
This lesson covers the most complicated fractions work fourth graders will be required to do. It involves a great deal of steps, so students will need to be organized and very careful workers. If you have not watched the previous fractions lessons, I suggest you do so before watching this lesson on adding and subtracting fractions with unlike denominators. I have not added a video for adding and subtracting mixed fractions with unlike denominators, because students perform those problems by simply combining all the skills we have already studied. The video for adding and subtracting fractions with unlike denominators is provided below. Underneath the video is a link to several practice problems. Word problems are also provided at the bottom of this page that require students to apply the skill in a real world situation.
Demonstration by: Libbie and Lillith
Practice Problems
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Sample Word Problems:
1. Erin and Darrell shared a tray of lasagna. Erin ate 1/5 of the lasagna. Darrell ate 2/3. How much of the lasagna did Erin and Darrell eat in all?
2. Ling took 2/10 of a pack of gum. Irving took 3/5 of the pack of gum. How much gum did they take from the pack?
3. Mom is baking for the school bake sale. She uses 1/4 of the eggs from the carton to make a cake. She uses 6/12 of the eggs to make cookies. What fraction of the eggs does Mom use while she is baking?
4. Jefferson ran 2/8 of a mile and Hank ran 2/3 of a mile. How much farther did Hank run than Jefferson?
5. Three-tenths of the school's fund raising goal was raised by the second grade. Four-fifths of the school's goal was raised by the fourth grade. How much more of the school's goal did the fourth graders raise than the second graders?
1. Erin and Darrell shared a tray of lasagna. Erin ate 1/5 of the lasagna. Darrell ate 2/3. How much of the lasagna did Erin and Darrell eat in all?
2. Ling took 2/10 of a pack of gum. Irving took 3/5 of the pack of gum. How much gum did they take from the pack?
3. Mom is baking for the school bake sale. She uses 1/4 of the eggs from the carton to make a cake. She uses 6/12 of the eggs to make cookies. What fraction of the eggs does Mom use while she is baking?
4. Jefferson ran 2/8 of a mile and Hank ran 2/3 of a mile. How much farther did Hank run than Jefferson?
5. Three-tenths of the school's fund raising goal was raised by the second grade. Four-fifths of the school's goal was raised by the fourth grade. How much more of the school's goal did the fourth graders raise than the second graders?
