This paper, drawing on the findings from empirical research project conducted collaboratively by the University of Sheffield, Lancaster University and the corresponding Local Councils in five state primary schools in England, examines productive use of verb collocations in assessment tasks by English language learners (ELLs) and English native-speaking (ENS) children. Learner test data from Years 4 and 5 at key Stage 2 (8-10 year olds) in each school was analysed in order to answer the following research questions: 1) in assessment conditions, targeting elicitation of subject specific knowledge through active production of written language (Author 1 & Author 3, 2019), what verb collocations do ELLs and ENSs rely most on, and 2) to what extent does learners’ use of verb collocations differ from that found in subject-specific primary dictionaries, science study books, and general corpora? The results revealed that both groups of learners produced collocations with general rather than specialised verbs most often, despite their frequent use in primary educational resources. Additionally, ELLs had difficulties with correct choice of prepositions for specific verbs and with syntactic and discourse aspects of the language, whereas ENSs did not experience these problems.