Bilingual or English only? How to teach vocabulary to dual language learners

We often hear about the benefits of bilingualism, but we can’t overlook the challenges it can bring. Some children begin learning a second language (L2), while their first (L1) is still developing. As early as preschool, these children—called dual language learners (DLLs)—can fall behind their monolingual peers in important areas, including vocabulary development. In order to ensure that this lag doesn’t continue, it’s crucial to provide effective vocabulary instruction as early as possible.

In this study, Méndez et al. tested whether a bilingual vocabulary instructional approach or an English-only approach would better improve the English vocabularies of preschool-aged Spanish-English DLLs. The only difference between the two approaches was the language(s) of vocabulary instruction. For 5 weeks, the preschoolers participated in small-group shared readings targeting 30 English words. Some key features of the intervention included repeated readings of culturally-relevant stories, many exposures to target words, multi-modal presentations, and child-friendly definitions.*

After 5 weeks, they found that the preschoolers learned more English and Spanish vocabulary from the bilingual approach than the English-only approach. By presenting information in both Spanish and English, it seems that the preschoolers were able to leverage their L1 knowledge to support learning in L2. The authors also found that the bilingual instruction was effective regardless of gender or the initial vocabulary skills of the preschoolers before instruction.


So, what’s the takeaway here? Even if you don’t have DLLs on your caseload at the moment, chances are you will in the future, so this matters for all of us. In order to be most effective, vocabulary instruction for preschool DLLs should include input in both languages. English-only instruction will not lead to better vocabulary outcomes for preschool DLLs. For the monolingual SLPs out there, don’t let this scare you! Think of it as an opportunity to get creative and collaborate with other professionals, family members, or L1 speakers in the community in order to support L1 development and L2 learning.  

*If you want to learn more about the specific instructional approach, the same authors provide more details in an earlier publication with a different group of preschool DLLs. Or, if you’re interested in SLPs’ roles regarding dual language learners, ASHA provides some great resources.

Méndez, L. I., Crais, E. R., & Kainz, K. (2018). The impact of individual differences on a bilingual vocabulary approach for Latino preschoolers. Journal of Speech, Language, and Hearing Research61, 897-909. doi:10.1044/2018_JSLHR-L-17-0186.