Background: Screen-sharing technologies enable applications such as screen mirroring, video streaming and instant messaging across multiple device screens. Despite their increasing use in many contemporary classrooms, there is a paucity of research directly examining pedagogical benefits and issues of these technologies. Objectives: This study investigated the influence of screen-sharing technologies on teachers' practices, highlighting pedagogical benefits and issues encountered. Methods: The paper drew on a sample of 321 K-12 teachers and utilised principal components analysis, descriptive statistics and inductive coding. Results and Conclusions: Teachers reported greater mobility, increased ease of content sharing and deeper learner cognition as attributes of improved learning and teaching with the technologies. However, a minority highlighted technical issues such as network and hardware problems affecting their confidence. Despite increased mobility as an affordance, teachers' perceptions about mobility largely appeared to be predicated on assumptions that the technologies were intended for didactic instruction. Takeaways: The study contributes to a more nuanced understanding of screen-sharing affordances while underscoring learner-led screensharing as a focus for future research and practice.