Mathematical Language Proficiency Contributes to Differences in Numerical Performance in Linguistically Diverse Third Graders

Language is a central predictor of mathematical abilities, and numerous studies have also highlighted the specific role of mathematical language. To this date, this was mainly investigated in linguistically rather homogenous samples. However, children with diverse language profiles (i.e., L1 vs. L2 learners) often have varying proficiency in the language of instruction, which can impact their math performance. Therefore, we explored the relation between mathematical language and basic numerical skills in linguistically diverse elementary-school children. Data was collected on 537 third graders in Luxembourg (M = 8.69 years), where the language of math instruction is German. 43% of children were L1 learners, while 57% were L2 learners, reflecting the multilingual and multicultural composition of the Luxembourg society. Language measures comprised receptive general vocabulary (nouns, verbs and adjectives) and mathematical language (spatial and quantitative terms). Basic numerical skills were assessed with five tasks: number writing and naming, number comparison, ordinal judgement and place-value identification. Further measures included rapid automatized naming and demographics (language profile, socioeconomic status, gender, age). Regression analyses revealed that mathematical and general language both significantly contributed to numerical performance, and that L1 compared to L2 learners showed higher performances. Results of a double mediation analysis indicated that mathematical language, together with general vocabulary, fully explained the observed performance gaps. These results confirm and extend previous studies reporting that lower language proficiency contributes to underachievement of L2 learners. Moreover, they emphasize the specific influence of mathematical language skills on numerical performance in third graders with diverse language profiles, extending the findings in younger children. Our findings thus highlight the importance of considering both general and mathematical language skills when assessing math performance in linguistically diverse elementary-school children. Vocabulary training and active use of mathematical language might help foster math abilities and reduce achievement gaps related to language profiles.