A onepager – or one-pager – is a one-page document that provides a story in several chapters. Online this stories are provided using one URL: so the users have to click only once to access the story.
This format is also known as scrollytelling. The name is telling: The users scroll to see and read the story, to discover the elements of the story.
For one-pagers you use text, videos, photos, graphics and audio. You bring them into an order that is logical: it must be easy for a user to follow your storyline. It may be chronological, or sorted by places or different persons you have interviewed. Possible is also a structure defined by sub-topics (different aspects of your story).
It is important to use the media type – video, photo, audio, text, graphic – which is most suitable for the specific part of the story.