Ask an Expert: Jim Cox and Pat Puleo
Measuring Up: A Parent's Guide to Testing, Grades, and Assessments

My son, who's in the sixth grade, scored at the 35th percentile in total math. His teacher told me that this is well below the norm. Should I be concerned?

Percentiles are ranks; by themselves they do not tell you how much a student does or does not know. Percentiles compare the scores of your son to a very large group of students nationwide (called the norm group) who took this test in the spring, 1995. The 35th percentile tells you that your son scored higher than 35 percent of the students in the norm group (and lower than 65 percent). The average percentile for the norm group was 50.

But look at the results in terms of "questions answered correctly." The sixth grade math test has 78 items. Your son got 37 of these items correct. The average student in the norm group got 44 of the items correct. (Incidentally, you can see that one can miss 34 items on this test and have it be "average" achievement.) These tests are constructed in such a way that students are expected to miss several items. Though your son is at the 35th percentile, he missed only seven items more than those at the national average of 50. In the big picture, seven items is really not very many on a 78 item test. Percentiles have a way of exaggerating the difference in achievement among the various ranks.

You will want to speak with your son's teacher about his strengths and shortcomings in mathematics. Consider his math grades, and look over his homework. However, I would use the 35th percentile as only one indicator of his overall achievement, and possibly not a very significant one when several criteria are considered. Remember, percentiles compare students on a scale. It doesn't matter how much difference there is among the number of items they answered correctly. So if a lot of students actually answer roughly the same number of items correctly, their scores expressed as percentiles will make it look like their scores are a long way apart, when really they are not.

TOP OF PAGE | BACK TO ARCHIVE INDEX