Here is another installment in my series reviewing the NY State Regents exams in mathematics.
The following question appeared on the June, 2014 Algebra 2 / Trig exam.
Graphs without scales are common on Regents exams (I’ve written about this before). Personally, it’s not a huge deal to me–I’m a lazy grapher, myself. However, a colleague of mine regularly complains about this, and she made an excellent point regarding the grading of this particular problem.
The solution to this problem involves translating the graph one-unit to the left and two units up. But since no scale is given on the graph, it’s not clear what one unit to the left would be. If we assume the box on the graph indicates one unit, then the red graph below would be appropriate. But if we assume a box to represent half-a-unit, the purple graph would be correct.
If no scale is explicitly given, it seems like both graphs should be considered correct and receive full credit. But the rubric doesn’t address this possibility, and it’s unlikely students were given the benefit of the doubt.