Due to the recent surge of immigration to Sweden, it is estimated that approximately 25% of students aged 7-19 are second language learners. This heterogeneous group of students poses a challenge for teachers across all subjects, due to diverse individual differences, varying levels of language proficiency and the unique linguistic characteristics of each subject.

Enhancing science literacy can be facilitated by incorporating a focus on comprehending words in context, as proposed by Logan and Kieffer (2021). Furthermore, functional science literacy, as defined by Norris and Phillips (2003), encompasses not only an understanding of science terms, but also the ability to effectively communicate, read, and write using these terms in non-technical settings. The project, Science and Literacy Teaching (SALT), funded by the Swedish Research Council, attempted to identify the best strategies for supporting science teachers in working with second language learners.

A model of word types was constructed, drawing upon the categorization of words into everyday common words, academic words, and scientific words, as proposed by scholars such as Nation (2013), Hulstijn (2012) among others. In order to assess the vocabulary difficulties faced by both first language (L1) and second language (L2) students, a sample of 232 participants was administered vocabulary tests that consisted of seven types of words. Three of these word types were neutral in terms of subject matter, while the other four were subject-specific and drawn from textbook texts in the fields of biology, physics, and chemistry. The tests were designed to examine students' receptive knowledge of the words, including their forms, meanings, and usage in authentic contexts. The tests involved matching test words with their correct meanings or synonyms in order to evaluate the depth of students' knowledge.

We found that there are four types of word groups that require special attention from teachers. In summary, L2-students had particular challenges with general language comprehension, such as academic words and homonymous words with subject-specific meanings. These types of words were not difficult for L1 students. Finally, all students had difficulty with homonymous words with academic and subject-specific meanings, as well as general subject-related words that were new to all students. This research provides insights into the challenges that second language learners face in science education, and the findings can inform the development of pedagogical strategies to support their learning. By addressing these challenges, the research makes a contribution to the field of multilingualism by improving our understanding of how to support second language learners in acquiring science literacy.

Hulstijn, J.H. (2012). The construct of language proficiency in the study of bilingualism from a cognitive perspective. Bilingualism, 15(2), Cambridge. Logan, J. K., & Kieffer, M. J. (2021). Investigating the longitudinal and concurrent relationships between polysemous word knowledge and reading comprehension among Spanish-English bilingual middle school students. Reading and Writing, 34, 301-335. Nation I.S.P. (2013), Learning Vocabulary in Another Language. Cambridge. Applied Linguistics. Cambridge University Press. Norris, S. P., & Phillips, L. M. (2003). How literacy in its fundamental sense is central to scientific literacy. Science education, 87(2), 224-240.