• Thirteen-year-olds: There were no statistically significant differences in average scores between 2004 and any previous year at any student-reported level of parental education.
• Seventeen-year-olds: The average reading score for students who indicated that at least one parent had some education after high school was lower in 2004 than in 1999 and 1980. For students reporting other levels of parental education, scores were not significantly different in 2004 from those in 1999 or 1980.

Parents' education levels: Students were asked to indicate their parents' level of education by choosing from the following options: graduated from college, some education after high school, graduated from high school, and less than high school. Results are not reported at age 9 because studies have shown that the responses are less reliable at this age.