

Let’s look at some items related to fractions to dig into this question. Here’s one from the grade 8 NAEP test in 2007. Only 49% of students answered it correctly. The most common incorrect response was E, which, oddly is the only sequence in which both the numerator and denominator go from greatest to least, the opposite of what the question requires. However clever our error analysis, we will never know if the selection of E represented a common misconception (that smaller numbers, in this case numerators, means bigger quantities when it comes to fractions) or just a futile guess with the last available choice.
Even individual correct responses can be deceiving. We did some field research for a fraction program Tom Snyder Productions is releasing this fall. We found students who consistently exhibited their understanding of adding fractions with problems like this one.


What we really need, I think, are layered assessments. The high level ones -- periodic achievement tests -- act as triage. They let us know which students need more in-depth diagnosis. But what troubles should we diagnose for? I suggest targeted key concepts, like those identified by the NCTM Curriculum Focal Points or the National Math Advisory Panel’s algebra foundations. Focus on the foundations, like fluency with whole numbers and fractions. Employ targeted, deep assessments to get a true window into what’s happening inside our struggling students’ heads.


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