Explaining is one of the fundamental teaching practices. Yet, much is still unknown about the ways in which pre-service secondary teachers (PSTs) learn to create instructional explanations. Even less is known about how technology can support PSTs in this process. This paper describes an instructional module which used video to enhance PSTs' knowledge of what a 'good' instructional explanation entails, and how to create one. In the module, implemented in a secondary methods course, PSTs first analyzed two video-based examples of instructional explanations from the web, and then created their own video explaining a concept or a proposition. PSTs analyzed all three videos, including their own, using the same rubric. In this paper, I describe the design and purposes of the module, discuss aspects of PSTs' explanations and examine the role of technology in developing PSTs' practice of creating instructional explanations.