Students facing a writing project suffer no differently from professional writers in many respects, but one aspect is especially bothersome: feeling stuck.
The particular importance of the "stuck" problem is that students don't see it as a natural writing problem. They see it as a problem with themselves. They think, "I just can't think of anything next." They feel that if they were not deficient, they would be able to write the entire paper without hesitation.
In reality, of course, as each section of a paper gets completed, the writer enters a new interval of creating something out of nothing: assembling the unseen elements of the next thought unit. If a student writer does not realize that these intervals will occur, the next step, instead of another paragraph, is increasing discouragement.
When teachers explain that these intervals are part of writing, and detail the process of getting through these intervals, students gain confidence to approach increasingly complex writing projects.