Hi Sarah! I personally like using storyboards to get client approval on content and then I create a prototype to get visual/design approval. I included a tidbit about prototypes in this article. I also made this free download to go with it.
The prototypes I’ve created are just a preview of what the entire course experience will be like. I just pull some content from the storyboard and build around 6-8 slides. For example, I usually include a title slide, content slides, a complex interaction, and a quiz slide. Then, as Richard mentioned, I publish it to Review 360 to get their feedback/approval before building out the entire course. There are many different ways to go about it. I just wanted to share one way that works for me. I hope that gives you some new ideas!