This study examined how well cognitive abilities predict high school students’ science achievement as measured by traditional content-based tests. Students (n = 1,651) from four high schools in three states were assessed on their science knowledge, reading skill, and reading strategy knowledge. The dependent variable, content-based science achievement, was measured in terms of students’ comprehension of a science passage, science course grade, and state science test scores. The cognitive variables reliably predicted all three measures of science achievement, and there were also significant gender differences. Reading skill helped the learner compensate for deficits in science knowledge for most measures of achievement and had a larger effect on achievement scores for higher knowledge than lower knowledge students. Implications for pedagogy and science assessment are discussed.

This study examines the benefits of reading strategy training on adolescent readers' comprehension of science text. Training was provided via an automated reading strategy trainer called the Interactive Strategy Trainer for Active Reading and Thinking (iSTART), which is an interactive reading strategy trainer that utilizes animated agents to provide reading strategy instruction. Half of the participants were provided with iSTART while the others (control) were given a brief demonstration of how to self-explain text. All of the students then self-explained a text about heart disease and answered text-based and bridging-inference questions. Both iSTART training and prior knowledge of reading strategies significantly contributed to the quality of self-explanations and comprehension. Adolescents with less prior knowledge about reading strategies performed significantly better on text-based questions if they received iSTART training. Conversely, for high-strategy knowledge students, iSTART improved comprehension for bridging-inference questions. Thus, students benefitted from training regardless of their prior knowledge of strategies, but these benefits translated into different comprehension gains. *This research was funded by grants to the first author from the NSF IERI program (REC-0089271) and the IES Reading Program (R305G040046). 147Ó 2006, Baywood Publishing Co., Inc.There is growing concern for U.S. students' ability to read, comprehend, and learn from text. For example, international comparisons show that students in the U.S. are falling behind students in other countries, especially on measures of reading comprehension. The National Assessment of Educational Progress (NAEP, 2003) indicates that 37% of fourth graders, and 26% of eighth graders cannot read at the basic level. The situation is even grimmer for minorities, with NAEP statistics indicating that over half cannot read at the basic level. These statistics indicate that a large proportion of adolescent students in the U.S. do not understand what they read.From a reading perspective, there are two general classes of reading deficits: decoding problems, such that the individual is not able to convert the written word to its phonological or semantic referent (e.g., Brand-Gruwel,

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We report results of 2 studies examining the relation between decoding and reading comprehension. Based on our analysis of prominent reading theories such as the Simple View of Reading (Gough & Tunmer, 1986), the Lexical Quality Hypothesis (Perfetti & Hart, 2002) and the Self-Teaching Hypothesis (Share, 1995), we propose the Decoding Threshold Hypothesis, which posits that the relation between decoding and reading comprehension can only be reliably observed above a certain decoding threshold. In Study 1, the Decoding Threshold Hypothesis was tested in a sample of over 10,000 Grade 5–10 students. Using quantile regression, classification analysis (Receiver Operating Characteristics) and broken-line regression, we found a reliable decoding threshold value below that there was no relation between decoding and reading comprehension, and above which the two measures showed a positive linear relation. Study 2 is a longitudinal analysis of over 30,000 students’ reading comprehension growth as a function of their initial decoding status. Results showed that scoring below the decoding threshold was associated with stagnant growth in reading comprehension. We argue that the Decoding Threshold Hypothesis has the potential to explain differences in the prominent reading theories in terms of the role of decoding in reading comprehension in students at Grade 5 and above. Furthermore, the identification of decoding threshold also has implications for reading practice.

Have you ever found it difficult to read something because you lack knowledge on the topic? We investigated this phenomenon with a sample of 3,534 high school students who took a background-knowledge test before working on a reading-comprehension test on the topic of ecology. Broken-line regression revealed a knowledge threshold: Below the threshold, the relationship between comprehension and knowledge was weak (β = 0.18), but above the threshold, a strong and positive relation emerged (β = 0.81). Further analyses indicated that certain topically relevant words (e.g., ecosystem, habitat) were more important to know than others when predicting the threshold, and these keywords could be identified using natural-language-processing techniques. Collectively, these results may help identify who is likely to have a problem comprehending information on a specific topic and, to some extent, what knowledge is likely required to comprehend information on that topic.