MIT App Inventor.
In an effort to make my students think about all of the menus, items, and media that their apps will need, I have my students using Google Slides to outline the design of their apps. They're doing this by having each slide in their slidedecks represent a screen in their apps. Then they're using the hyperlinking function in Google Slides to link between the slides in their slidedecks. Again, that's done to simulate tapping screens in the apps they're designing. In the following video I explain this process a bit more.