10 eLearning Freebies: Instructional Design and eLearning: Tips, Advice and Reviews
Free templates, sound effects, graphics, and more
15+ eLearning Storyboard Templates « Flirting w/ eLearning
This is screenshots of storyboards, rather than links to actual templates, but good inspiration for different ways to lay out a storyboard and examples of what to include.
Storyboarding Branched Scenarios - ThinkingKap
This is something I've struggled with--a good method for storyboarding branching scenarios. I've used several different Word and PowerPoint templates in the past, none of which have quite worked the way I wanted. I can write the branching in a linear document without much trouble (I once drafted one longhand in a notebook), but it makes my SMEs brains explode to try to follow them. I've seen recommendations for Twine in the past, and this explains in more detail how it works as a storyboarding tool.
Storyboard your ideas in PowerPoint
Install the free version of Visual Studio to add Storyboarding tools to PowerPoint. These are intended for web and app development, but you could use these tools for elearning storyboards by following the first part of the instructions (ignoring the parts about linking to backlog items with a team).