[2] In the 2004 followup for the ECLS kindergarten class of fall 1998, 86% of cohort members were in fifth grade, 14% were in a lower grade, and less than 1% were in a higher grade. For the sake of simplicity, students in the ECLS followups are referred to by the expected grade; that is, they are referred to as first graders in the spring 2000 assessment, as third graders in the spring 2003 assessment, and as fifth graders in the spring 2004 assessment.

[3] The poverty status variable in ECLS is based on information provided by the parent. The variable is derived from household income and total number of household members (Princiotta, Flanagan, and Germino Hausken 2006). Federal poverty thresholds are used to define households below the poverty level. For example, if a household contained two members, and the household income was lower than $12,015, the student was considered to be living below the poverty threshold.

[4] Socioeconomic status was based on five equally weighted components: father's education, mother's education, family income, father's occupational prestige score, and mother's occupational prestige score.

[5] NAEP consists of three assessment programs. The long-term trend assessment is based on nationally representative samples of 9-, 13-, and 17-year-olds. It has remained the same since it was first given in 1969 in science and 1973 in mathematics, permitting analyses of trends over three decades. A second testing program, the national or main NAEP, assesses national samples of 4th, 8th, and 12th grade students. The national assessments are updated periodically to reflect contemporary standards of what students should know and be able to do in a subject. The third program, the state NAEP, is similar to the national NAEP but involves representative samples of students from participating states.

[6] These recent trends are based on data from the national NAEP program. The current national mathematics assessment for grades 4 and 8 was first administered in 1990 and was given again in 1992, 1996, 2000, 2003, and 2005. In 2003, only fourth and eighth grade students were assessed. The current grade 12 mathematics assessment has only been administered once: in 2005. Trend analyses for grade 12 mathematics are therefore not available. The current national science assessment was first administered in 1996 and was given again in 2000 and 2005.

[7] Although the NAEP program collects information about eligibility for the free or reduced-price lunch program for grade 12 students, it does not report these data. Because other reasons for not applying for school lunch programs (including food preferences, ability to buy lunch outside school, and wanting to avoid embarrassment) generally increase with student age, program eligibility becomes an increasingly unreliable indicator of poverty at higher grade levels. For example, approximately 35%–45% of fourth grade and 30%–40% of eighth grade public school students have been eligible in recent years for the subsidized lunch program. In contrast, only about 15%–25% of 12th grade public school students have been eligible (determined using the online NAEP Data Explorer tool at The relatively low percentage of grade 12 students noted as eligible for the program raises concerns that it is not a reliable indicator of low family income for these students.

[8] Insufficient sample size in 1990 for Asian/Pacific Islanders and American Indians/Alaska Natives precluded calculation of reliable estimates for this group. Increases in average scores for Asian/Pacific Islanders in grades 4 and 8 were observed between 2003 and 2005. Scores increased for grade 4 American Indians/Alaska Natives between 2003 and 2005, but not for grade 8 American Indians/Alaska Natives.