I am looking forward to going over this quiz question with my Geometry students:

 

I recently added "part a" to this assessment, "How is XT related to XZ?" before asking students to actually solve the problem for this very reason:  I want to know what specific misconception, if any, the student has about the learning target, not just if they're able to setup and solve the linear equation. 

If Suzy realizes that XT is half of XZ (part a), then how could 2x + 11 = 5x + 8 (part b)? 

Name that misconception (and how to help students overcome it)!