Formative Assessment 72

Assessment Problem: 

Graph the equation y=x+4.
Jimmi said that this line would go through the axis at (4,0) because in the equation you add 4 to x. Do you think that Jimmi was right?

Common Responses: 

Many students agree with Jimmi.

Mathematical Issues: 

When creating algebraic equations for linear functions, student commonly place the value of the x-intercept into the equation “y=mx+b.” See also Connecting graphs to algebraic relationships, The missing x-intercept value in y=mx+b, and The value of “b” in “y=mx+b”.

Domain: 
Analysis of Change
Theme: 
Linear Functions
Common Core Standards: 
F-IF: Interpreting Functions
Research References: 
Moschkovich, J. (n.d.). "Students" use of the x-intercept as an instance of a transitional conception. Educational Studies in Mathematics, 37(2), 169.