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Lecture-Based: Common Denominator

Media Type:
Video

Running Time: 4m 07s
Size: 3.8 MB

or

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A common denominator is needed when adding fractions with differing denominators. The pre-algebra concept of combining like terms is briefly noted.

These resources are part of KET's Math Instructional Strategies: Number Operations collection.

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Background Essay

Students may sometimes be unsure when adding or subtracting fractions with differing denominators. In this situation, the idiomatic expression, "You can't add apples to oranges" may come to mind. Finding a common denominator is the solution when adding or subtracting fractions with differing denominators. The concept of like terms can be glimpsed as a result of finding the common denominator.

Discussion Questions

• Describe ways that visual representations (the pizzas on the board, etc.) can be effective. Are there times that this type of representation is ineffective? Explain.
• In your opinion, which was the more effective visualization in this video: the pizzas on the board or the writing utensils example? Why?
• The multiplicative identity states that the product of any number and 1 is the number itself. Is this explicit or inferred in this lesson? Would you point it out? Why or why not?

Standards

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