What professors want instead of volume is an organized piece of writing. Use headings and other affordances of writing. Remember, white space is your friend.
Paragraphs are essential. Keep each wrapped around a specific idea. Group these paragraphs under headings. The goal is to provide a map of meaning for readers that they do not have to infer.
You want to have an explicit organization for readers, but also do it with a little bit of dazzle. You are correct. Sentence variety and and transitions are important tools in our chest. Keep some short. Other times we may flip the predicate or combine sentences together.
Our transitions have to combine organized writing in creative ways so you do not bore your audience with tales of, “In this piece I am going too..” Look back at this comment. You will always find a connection between two words. One in the last sentence and the other in the first. less or more=volume, map of meaning=explicit organization.
We will explore all of these techniques in our class.