Abstract

CLIL streams in Germany have long been understood as an elitist approach. Although many schools have started to open their CLIL streams to a larger number of students, in general allowing all students together with their parents to choose CLIL schooling, other schools still select their students based on a variety of high achievement criteria. Considering this selective nature, CLIL students’ success in acquiring high levels of language proficiency while maintaining or even surpassing their peers in mainstream EFL classes in content knowledge is not surprising. Researchers thus need to consider to what extent these often found above average achievement outcomes may be explained by positive selection biases of students into CLIL streams. This study investigated the composition of CLIL versus EFL classes with regard to a number of students’ individual difference and background variables (i. e. gender, age, SES, home language (L1) and cognitive abilities). The overall sample consisted of 380 year 9 students from 16 classes and nine different grammar schools from the Ruhr area in North-Rhine Westphalia, Germany. Language proficiency was measured by the last grade in English and a C-Test battery. The typical CLIL students in the present study were younger, of higher SES, and scored higher on the cognitive functions test (CFT) than their peers in EFL classes. As expected, CLIL students also received better grades in English and scored significantly higher on the general language proficiency test (C-Test) than EFL peers. Structural equation modelling however showed that controlling for the positive selection bias into CLIL classes did not change the strong positive effect of CLIL on language proficiency. These results suggest that the previously reported positive effects of CLIL are not explained by the existing selection bias.