I'll ask her, Bob. Do you have any suggested activities and/or assessments you recommend for pre-algebra or algebra classes?
Also, I liked this activity you posted. I am just interested in how the 18 students missed it. It shouldn't be news to anyone here that problems requiring original (not prior art) solutions are typically "too hard" for the majority of students. That has always intrigued me even when I was a kid. Prior art and convention is very important and goes with the territory, but curriculums, especially current ones, stop short of asking students to solve original problems. And I don't mean highly competitive exam problems, just word problems with unique circumstances.