Paper prototyping and storyboarding on sheets of paper are great ways to brainstorm and design proposed processes within mobile apps.
When designing a software application it can become extremely complex really quickly. If you start your initial designs in a design application like Sketch, Indesign, Figma, it can be very challenging to quickly make design changes that require a lot of rework. Also, because of the computer and software being intermediaries between your ideas and your design, they slow the idea process down.
Creating paper prototypes and storyboards are the best ways to get your ideas out of your head and in a visible format. You and your team then can observe and test your ideas. Also, starting with hand-drawn paper prototypes helps people focus on the ideas without getting lost in the aesthetic details.
There are several ways you can leverage this type of brainstorming. You can sketch out scenarios you imagine when people would be using your app. Another method you can do is to sketch out potential screen designs and test out a few different processes.
I’ve been working on designing a travel app and have been using the paper prototyping method. I absolutely love it and will always use it from now on.