The purpose of this paper was to examine if primary school pupils had the understanding of technical words in an expository text they work with in the Swedish subject. Since Sweden is a multicultural society and that it is increasingly common to meet children from different backgrounds and with other mother tongue than Swedish, was the focus of this study to investigate this purpose from a second language perspective. Based on the argument that studying a text statement, a more complete picture of the language and severity of the text can be given, the first parts of the empirical study focused on investigate and measure the readability of an expository text that pupils use in school. Furthermore, out of the research hypothesis that words longer than six letters can cause some difficulties for readers, the second part of the analysis consisted to find out how many long words the text consist of. Technical words were picked out of this wordlist and a multiple-choice task was created to test pupil ́s breadth of knowledge of these technical words. The data results showedthat second language pupils did better on the test than first language pupils, possibly due to the fact that the first language pupils had poorer text-related knowledge about the text subject and thus less vocabulary in this area than the second language pupils.