Reflection: Checks for Understanding Expand Algebraic Expressions Using the Distributive Property - Section 2: Guided Problem Solving


My students were able to do the first 4 problems with relative ease.  Emphasis on relative; there were still some difficulties.  While they were able to "do" the math, they still didn't understand that they were essentially finding the product of two numbers.  Going back to simple numeric examples helped students see the connection to some degree.  Even more beneficial was to substitute a value into the variable and evaluate.  Then expand the expression and substitute the same value.  Students then saw the equivalence and saw a bit more clearly that an expression in the form of a(bx + y) can be seen as the product of two numbers.  

Using GP1 as an example:   

15 (2b + 3) = 30b + 45

If we let b = 1:

15 (2*1 + 3) = 30 * 1 + 45

    15 (5) = 30 + 45

       75   =    75

 Several students were still a bit stumped on GP7 - finding the area of a rectangle.  They all know how to find an area of a rectangle; I'm sure a few think you can find the area of any shape by multiplying length times width!  So just multiply 5 and (3x + 8) to find the area of the rectangle! 

Students are exercising mathematical practices 2 and 7! 


  The Product of Two Numbers
  Checks for Understanding: The Product of Two Numbers
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Expand Algebraic Expressions Using the Distributive Property

Unit 4: Expressions and Equations
Lesson 2 of 20

Objective: SWBAT expand linear expressions using the distributive property

Big Idea: Expand expressions involving positive and negative rational numbers (mostly integers) using the distributive property.

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18 teachers like this lesson
Math, Expressions (Algebra), distributive property, expand linear expressions, equation
  50 minutes
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