Unit 6, Lesson 8
Equal and Equivalent
Grade 6
Preparation
Lesson Narrative
In this lesson, students are introduced to equivalent expressions. Two expressions are equivalent if they always have the same value. If two expressions with variables are equal whenever the same value is substituted for the variables, the expressions are equivalent.
Students begin by using tape diagrams to justify whether two numerical expressions are equal. They then use tape diagrams to represent two expressions with variables when given a value for the variable. They use the diagrams to distinguish between equivalent expressions, which have the same value for all values of the variable, and expressions that may be equal for some, but not all, values of a variable. Students then identify simple equivalent expressions, using the structure of the expressions and what they know about the relationships between operations and their properties (MP7).
- Explain (in writing) that some pairs of expressions are equal for one value of their variable but not for other values.
- Justify (using words or other representations) whether two expressions are “equivalent,” or equal to each other for every value of their variable.
Let's use diagrams to figure out which expressions are equivalent and which are just sometimes equal.
Required Materials
Activity 2
Required Preparation
None