The paper investigates the linguistic challenges faced by Setswana-speaking Grade 7 learners when writing Science examinations in English. In South African schools, non-mother tongue speakers of English learners are only introduced to English as a language of learning and teaching in Grade 4, which creates problems for these learners because English is foreign to them. The purpose of conducting this research was to help policymakers meet the linguistic needs of non-native English speakers, make curriculum development specialists aware of the linguistic challenges faced by non-native speakers of English and help readers gain a better understanding of why some teachers prefer to use indigenous languages when they teach in English. The participants comprised four purposively selected Grade 7 Natural Science teachers, two school governing bodies (SGBs) and Grade 7 learners from two primary schools in Hammanskraal, Gauteng. Data gathered indicated that Setswana-speaking learners made basic errors related to spelling, sentence construction, grammar, incomplete sentences, mixed languages, using words that do not exist, tenses and understanding instructions. As a result, SGBs should consider these linguistic challenges when they draft language policies for rural and township schools.