Imagine your reader, not your professor
While it is true your lecturer/tutor/professor will actually read your paper, these people are markers. Markers judge how well yours and your classmates' papers communicate to an intelligent but slightly less informed reader. Markers would ideally like their students to write papers in as few words as possible but being clear is so much more important than writing a short paper. Write for a reader, not a marker, and this should help make your writing clearer.
Imagining such a reader can be complicated when writing academically for Science, Technology, Engineering, Maths, or Medicine (STEMM) subjects. These topics are complex and require clear logical reader-friendly explanations and definitions. Even with a clear imagined reader in mind, you need to be very clear and explicit about the destination of your paper. Sections, paragraphs and sentences should logically build toward such destinations and signpost them in advance.
Your STEMM writing requires a clearly communicated destination
For example, if you know that the final sentence of a section is going to be:
"The aim of this new experiment is to test the effectiveness of X in situation Y."
then before arriving here the reader will need to learn what X is, what situation Y is, and how this new experiment differs from old experiments to test X's effectiveness. Writing a section of a paper like this requires planning and editing as you work backwards to build the clear and logical steps to reach this sentence/destination. Both planning and editing take considerable amounts of time in addition to the drafting.
Give clear indications of what is coming
When drafting, your writing should be reader-friendly; it should give clear indications to the reader what the following sections, paragraphs and often the remaining parts of the sentences will be about. Below are some phrases which demonstrate ways writers give clear indications:
"In order to accomplish X, two types of samples were characterised in this work. We now consider the connection between B and C. To address this question, we used tool J, which is composed of … There are several alternatives to this approach. The difficulty of obtaining a reliable model has been well documented."
With each of the examples above, the reader should have a good indication of what is going to follow. There shouldn't be any surprises as they read their way to the next destination.
Precision can make writing simpler
Academic STEMM writing requires precision and such precision can make the writing easier. There is no great need for you to find different ways to say the same thing. In STEMM writing, new and different names for the important nouns or adjectives or verbs are likely to confuse your reader. Your reader needs to know if something is new or has been mentioned before. Replacing a noun with a new noun without signposting this change is not reader-friendly.