The present study investigates how academic coursework and formal learning of instructional technology and materials design help pre-service English language teachers' development of critical knowledge of CALL materials. The participants are 111 pre-service English language teachers enrolled in a TEFL programme at a Turkish University. Throughout a 14-week semester, these participants learn to design a variety of CALL materials including online teaching tools and a set of Web 2.0 tools. The article explores the skills and knowledge of pre-service teachers on the design and development of audio-visual web-based activities, through qualitative content analysis of their written reflections. The analyses of reflections on practice have revealed that these teachers demonstrate strong and critical understanding of CALL in enriching authenticity, enhancing motivation, facilitating language learning, and providing multimodal resources. They also display great awareness of instructional knowledge, in particular, in the design and interface of technology to facilitate learning.