Background: In South African primary schools, reading is central to curriculum delivery, with a structured three-step process: pre-reading, while-reading and post-reading. Many learners struggle with reading comprehension, which affects their academic performance. Research emphasises the importance of pre-reading for activating prior knowledge, expanding vocabulary and developing metacognitive skills. Open educational resources (OERs) support these processes by aligning with the 'four Rs' of openness: reuse, revise, remix, and redistribute. Objective: This study investigates the adoption of an OER designed to support teachers and improve pre-reading instruction. Method: Fourteen English home language and first additional language teachers participated in this qualitative multiple case study. The OER aimed to be beneficial and accessible. Data were collected through interviews and thematic analysis. Results: The OER facilitated partial implementation of pre-reading activities. Teachers activated learners' background knowledge and focused on vocabulary development. However, language structures, conventions, inference, and literary knowledge were underused. Teachers reused and revised the OER for specific contexts, but did little remixing or redistributing. The OER's usefulness was contingent on its accessibility. Although it made reading lessons more engaging, it did not fully implement all prereading steps. Conclusion: The success of an OER in improving teaching and learning depends on its design and accessibility. While background knowledge and vocabulary development were prioritised, more attention is needed for language structures, reasoning, and literacy knowledge. Contribution: Teachers would benefit from professional development focusing on the optimal use of OERs, especially in remixing and redistributing them.