Disciplinary vocabulary and mastery of educational objectives in first-grade

Background: In contrast with general academic words, disciplinary academic words have been less studied, in particular their frequency in educational materials and their contribution to educational outcomes in the early grades; therefore, there are no strong scholarly recommendations about teaching these words to young students. A better understanding of the importance of these words for young learners may complement our understanding of vocabulary's role in education and learning, as well as support the development of more effective interventions. Aims: To measure the contribution of children's knowledge of science and social studies disciplinary words to their mastery of educational objectives. Sample: One-hundred-and-seventy-four Chilean first-grade students in 26 schools. Methods: We identified the general academic and disciplinary vocabulary present in 272 science and social studies materials. Using frequency and pedagogical criteria, we selected a set of science and social studies words, as well as general academic words, and assessed their knowledge in 174 Chilean first graders. Later we administered tests of the children's mastery of educational objectives in the two subjects. Using mixed-effects regression analyses, we examined the contribution of each type of word to mastery of educational goals. Results: Disciplinary words were frequent in first-grade materials, but only science, not social studies words, had a significant contribution to children's mastery of the educational objectives after controlling for general vocabulary, general academic vocabulary, and working memory. Conclusions: Disciplinary words are frequent, and science words specifically are relevant for first-grade educational objectives. Vocabulary interventions should include both general academic and disciplinary words.