Differences in the mastery of organizational features and in the use of lexical-grammatical resources in scientific explanations by fourth graders

Although there are studies about discursive and lexicogrammatical resources displayed in explanations produced by school students, less research has been developed about them in Spanish on disciplinary genres written by primary school students. In this article we will describe, compare and relate discursive organization, resources linked to writing –length measured in amount of words and clauses, lexical diversity and syntax complexity– and those resources specific to academic language –academic vocabulary, scientific vocabulary, nominalizations and causal links– included in scientific explanations produced by Chilean fourth-graders of three schools from different socio-economical groups. Three hundred twenty-six explanations were transcribed and analyzed using CLAN (Computerized Language Analysis) for the automated and semi-automated measures. The explanations were compared according to the following variables: sex, socio-economical group, and topic of the explanation. T and ANOVA multifactorial tests were applied for the data analysis. The findings show significant differences in the use of different lexicogrammatical resources when compared using the mentioned variables. Regarding discursive organization, the explanations produced by the students integrate affirmations, but not evidence, the latter being the distinctive discursive phase of this disciplinary genre. Consequently, this research highlights the need to design explicit teaching proposals that promote the development of epistemic writing skills in the school context in order to foster the learning of academic language and disciplinary literacy.