SA-eDUC Vol 2 (1) 1-9 1 SA-eDUC JOURNAL Volume 2, Number 1, pp. 1-9 10 December 2005 The influence of language proficiency on geometric thinking Annalie Roux Faculty of Educational Sciences, North-West University, Potchefstroom Campus snsar@puk.ac.za Abstract: Concern regarding the extent of underachievement in mathematics has been expressed by many authors. The role of language proficiency of the learner as a causal factor in this underachieve- ment has been neglected. Researchers found sufficient evidence to conclude that language proficiency is related to mathematics achievement. In mathematics, symbolic language fills a dual role: as an instrument of communication and as an instrument of thought by making it possible to represent mathematical concepts, structures and relationships. According to Van Hiele lan- guage structure is a critical factor in the progression through the Van Hiele levels, from visual, concrete structures to abstract structures. This article reports on a research project that inves- tigated the influence of language proficiency on geometric thinking. One hundred and fifty-two Grade 8 and 9 learners completed two tests each. One test measured language proficiency in their mother tongue and the second was a geometric test based on the Mayberry-type Van Hiele test for assessing learners' geometric thinking levels. Language proficiency was taken as the indepen- dent variable and geometric thinking as the dependent variable. In the analysis of the results, the top 25% and bottom 25% performers in the language proficiency test were taken. The perfor- mance of these two groups was compared to their performance in the geometry test, to determine if there was a significant difference in the performance of the more proficient language learners and the less proficient language learners with respect to each of the first three Van Hiele levels. Results showed a practical significant difference between the performance of the more proficient language learners and the less proficient language learners with respect to each of the first three Van Hiele levels, but also with respect to the geometry test as a whole. In particular, two aspects of language proficiency, namely, reading comprehension and vocabulary, appeared to be very strong predictors for geometric thinking on the first three Van Hiele levels. Introduction Concern regarding the extent of underachievement in mathematics (in South Africa, but also worldwide) has been expressed by many authors. According to research conducted by the Human Sciences Research Council (HSRC), South African learners in Grade 8, who took part in the Third International Mathematics and Science Study Repeat (TIMSS-R), ended up at the bottom of the list of 38 participating countries (Howie, 1999:9). National and international surveys of mathematical performance reveal that secondary school learners cannot identify and name shapes like the kite, rhombus, trapezium, parallelogram and triangle (Triadafillidis, 1995:225). Learners' performance is even poorer when it comes to items involving the understanding of features and properties of shapes. Problem statement The role of language proficiency as a causal factor in this underachievement has often been neglected. In this research project I attempted to find an answer to the following question: Does language proficiency have an influence on geometric thinking?