The vocabulary instruction of Chilean kindergarten teachers

Children's oral language skills, particularly their vocabulary knowledge, play a central role in literacy development (Dickinson & Tabors, 2001; Snow, Burns & Griffin, 1998). Yet class-based differences in children's vocabulary development surface around two years of age and only widen over children's lives (Hart & Risley, 1995; Schady, 2011). For low and middle income (LAMI) countries working to improve literacy rates, this gap is of particular concern. Early childhood education (ECE) programs can help mitigate these differences if high levels of classroom quality can be achieved, but more needs to be known about contributors to such quality. This study evaluates the effectiveness of teacher professional development in supporting practices that promote children's vocabulary development. Classroom videotapes gathered during a cluster-randomized evaluation of a coaching-based professional development program in Chile were analyzed to identify the intervention impacts of training on Kindergarten teachers' explicit vocabulary instruction and the relationships between aspects of instruction and children's vocabulary outcomes. Two important findings emerged. First, UBC training increased the probability that literacy instruction would occur by 26 percent and that vocabulary support would be provided during literacy by 23 percent. Given the presence of these forms of instruction, training increased literacy instruction by 13.68 minutes and increased vocabulary support during literacy by 2.48 minutes. However, UBC training reduced the probability that other-topic instruction would occur by 25 percent and the probability of vocabulary support during other topics by 36 percent. Given the presence of these forms of instruction, training reduced other-topic instruction by 9.26 minutes and vocabulary support during other topics by 5.35 minutes. Second, each additional standard deviation of conceptual information about words made available predicted a 0.10 standard deviation increase in children's vocabulary outcomes, when controlling for the density and diversity of teachers' language, time in explicit vocabulary support and child and teacher demographics. More conceptual information was provided during other-topic (e.g., math, science or social studies discussions), rather than literacy instruction. Although, it increased literacy instruction, training had the unintended effect of reducing time spent in such concept-rich discussions. Practice and policy implications of these findings are discussed.