How do you add fractions with unlike denominators? Find common denominators of course! You know, however, that I’m a big proponent of students understanding why they are using a strategy. If our students don’t know why they are using a strategy so many of our learners don’t know when to apply that strategy. They become students who have “strong rote skills but struggle with application”.
Don’t tell me you have never uttered that phrase at a students’ problem-solving meeting. We all have 🙂
An incredibly effective method of helping our students to understand strategies is to give them concrete and representative experiences to make sense of an abstract strategy. I want to share two representational strategies for adding fractions with unlike denominators.
Representational Models for Adding Fractions
Your students may suggest creating two like arrays. In the example to the right, You can easily draw eighths over top of the fourths and fourths over top of the eighths to create two arrays each with 32 pieces.
Once the two arrays are equal it is easy to add the two fractions together because you have found a common denominator of 32!
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