Formative Assessment 49

Assessment Problem: 

1. Solve the equation 2(3x+4) = 6x + 8
2. After solving, could you solve it in another way?
3. What would be the relationship between the graphs of each side of the equation?*

Common Responses: 

The correct answer is all real numbers.  It has infinitely many solutions.  This equation is an identity. Graphically each side of the equation represents the same line (lines are collinear). 43% of high school student-pairs answered this question correctly. 71% of the participants used symbolic manipulation as their first choice of strategy.

Domain: 
Algebraic Relations
Theme: 
Solving equations
Common Core Standards: 
6.EE Expressions and Equations
Research References: 
(Huntley, Marcus, Kahan, & Miller, 2007)