Here are three different ways to get around PowerPoint Slide Show taking up both screens so that you can have PowerPoint slides on one (shared) screen and the Zoom video gallery on the other.
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Walking Trails with VoiceThread
In this Faculty First-Person post, Environmental Sciences senior lecturer Anne Larson Hall talks about how students in her freshman seminar used VoiceThread, a collaboration and multimedia presentation tool, to take classmates along on hiking trails they had hiked or would like to hike.