Determine if two expressions are equivalent by combining like terms, distributing, factoring, or any combination of those. For combining like terms, students will first use algebra tiles, then algebraic expressions. Next, give your students this challenge:

The directive, *identify when two expressions are equivalent,* is much too vague.

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Conclude by leading this investigation:

Recamán’s Sequence

by MathPickle

6.EE.A.4: Identify when two expressions are equivalent (i.e., when the two expressions name the same number regardless of which value is substituted into them). *For example, the expressions y + y + y and 3y are equivalent because they name the same number regardless of which number y stands for..*