When I create storyboards in MS PowerPoint, I find the Outline tab incredibly useful. You can find this tab in the top left corner, behind the Slides tab that shows the small image of each slide in your presentation.
The Overview tab gives a ‘big picture’ view of your presentation. It just shows the title of each slide, and the text of the slide. When you press the Enter key in this panel it will create either a new line. You can then use the Shift and Shift + Tab keys to increase or decrease the indent of that text. If you Shift + Tab as far as you can go, the text becomes a new slide.
The way I use this feature is to quickly create one slide for each section of my course. Then I brainstorm the topics within that section. I initially create these topics as bulleted points within a slide, but then I reproduce them as separate slides. I tend to number my sections and topics (e.g. Section 1, Topic 1a) so that I don’t lose track of the hierarchy at this point.
It’s easy to drag and drop slides into a new order, or to cut and paste, in this format. And when I’m finished I can see how many slides I have; and if I assume each slide is about 1 minute of content I can estimate the overall length of my module.