The impact of multi‐word units in early foreign language learning and teaching contexts: A systematic review

This systematic review reports on research investigating the impact of multi‐word unit (MWU) input on young learners' second language (L2) attainment in instructed settings. Recent findings suggest that L2 learners can generalise from MWU input, abstract patterns and employ such schemata productively via slot‐filling, indicating that MWUs are key catalysts of learners' L2 development. Simultaneously, primary school L2 instruction is on the rise worldwide and the importance of MWUs is acknowledged in curricula, teacher education and teaching materials. Therefore, the incentive of this review is to systematically report the state of the art of research regarding the impact of MWU instruction in early L2 teaching contexts. The review covers English, German and French research into typically developing monolingual children aged 5–12 learning an L2 in instructed teaching settings. Only two of the total results (n = 2233) met the inclusion criteria. Following quality assessment using the Mixed Methods Appraisal Tool and based on a narrative synthesis of available results, we cannot report trustworthy evidence of the effectiveness of teaching MWUs to young L2 learners. We highlight the lack of research evidence and conclude that existing research lacks robust evidence that MWU input already established in teaching contexts has a measurable effect on specific aspects of students' L2 attainment, such as productive skills. Although we promote MWU's potentially facilitating role in L2 development, we call for more classroom‐based intervention research on MWUs in primary school contexts to enable much‐needed evidence‐based recommendations for L2 teaching to support L2 learning outcomes in primary schools. Research has shown that multi‐word units (MWUs) are key catalysts for L1 and L2 learning. MWUs are crucial to current primary school L2 teaching and their importance is acknowledged in curricula. This review systematically examines the scientific evidence for the effectiveness of MWU instruction on L2 attainment.Our review cannot report trustworthy evidence of the effectiveness of teaching MWUs to young L2 learners. This lack of evidence is striking since early L2 instruction is on the rise worldwide and MWUs are already integral parts of L2 curricula, teacher education and teaching materials.Given our findings, we call for more research in instructed settings to better understand the impact of MWU input on specific aspects of students' L2 attainment, such as productive skills. Based on such work, researchers could provide policy makers and practitioners with evidence‐based recommendations that help integrate MWU input into L2 curricula and teaching in such a way that is most beneficial for young students' L2 attainment.