We determined the relative importance of the so-called approximate number system (ANS), symbolic number comparison (SNC) and verbal and spatial short-term and working memory (WM) capacity for mathematics achievement in 1,254 Grade 2, 4 and 6 children. The large sample size assured high power and low false report probability and allowed us to…

In this article we present a new method for estimating children's total vocabulary size based on a language corpus in German. We drew a virtual sample of different lexicon sizes from a corpus and let the virtual sample "take" a vocabulary test by comparing whether the items were included in the virtual lexicons or not. This enabled us to…

The development of scientific thinking was assessed in 1,581 second, third, and fourth graders (8-, 9-, 10-year-olds) based on a conceptual model that posits developmental progression from naïve to more advanced conceptions. Using a 66-item scale, five components of scientific thinking were addressed, including experimental design, data…

This longitudinal study was conducted to determine (a) the rate of co-occurrence of reading disabilities (RDs) in a writing disability (WD) population of students followed from first grade to fourth grade and (b) the cognitive burden that is assumed by having a WD and a RD (WD + RD). The sample included 137 first-grade students from a single…

This study addresses whether reading involves a process termed semantic and phonological ability to adjust recoding (SPAAR). It was hypothesized that SPAAR helps readers link inaccurate pronunciations to lexical entries (e.g., "spynitch" to "spinach"). Psychometric properties of the Mispronunciation Correction Task (MCT), a…

D. Elkonin's thesis that thinking is much more closely related to writing than to oral speech formed the basis of our three-year formative experiment at the elementary school level. In order to test this idea, second-graders through fourth-graders were given a few assignments in which they were asked to exchange thoughts in writing with their…

Recent studies have emphasized that developmental dyslexia is a multiple-deficit disorder, in contrast to the traditional single-deficit view. In this context, cognitive profiling of children with dyslexia may be a relevant contribution to this unresolved discussion. The aim of this study was to profile 36 Portuguese children with dyslexia from…

Using 4 years of mathematics achievement scores, groups of typically achieving children (n = 101) and low achieving children with mild (LA-mild fact retrieval; n = 97) and severe (LA-severe fact retrieval; n = 18) fact retrieval deficits and mathematically learning disabled children (MLD; n = 15) were identified. Multilevel models contrasted…

We report a longitudinal study investigating the predictors of reading comprehension and word reading accuracy between the ages of 7 to 8 (UK Year 3) and 10 to 11 years (Year 6). We found that different skills predicted the development of each. Reading comprehension skill measured in Year 3 was a strong predictor of comprehension in Year 6;…

Both reading and language experiences contribute to vocabulary development, but questions remain as to what effect each has and when. This article investigates the effects that reading, telling and sharing a story have on vocabulary acquisition. Children (N = 37) were told nine stories in a randomized, single-blind and counterbalanced 2 × 3 mixed…

Two groups of 8- to 10-year-olds differing in rapid automatized naming speed but matched for age, verbal and nonverbal ability, phonological awareness, phonological memory, and visual acuity participated in four experiments investigating early visual processing. As low RAN children had significantly slower simple reaction times (SRT) this was…