You are browsing Twitter.com and see an interesting image. So you just click on the image / media to view it larger. As you can see in the image, the size is 503 pixels by 510 pixels, above screen-shot was taken in Full Screen mode.
How people, learn ?
They view videos, take notes, research and they don’t do all of this at one go. There are breaks and most prefer to do it offline, not bound by the progress of a browser window limiting and dictating your pace.