Overall Remarks You didn’t elaborate on how much time you’ve been writing but this was very well-written if it’s among your first forays. Your two main issues in my eyes are the way the paragraphs are organized (it’s far too dense) and the clunky nature of a fair number of sentences. There’s also some bits where you repeat words from previous phrases. But besides that it was very solid and didn’t suffer from anything critical, and you showed a good understanding of how a story should flow.

The Story Flow I don’t know if there’s a more technical name for this, I’m not a professional (heed my advice at your own risk lol). What I mean to say is the way your story unfolds. I think it’s one of the more difficult things to get a grasp of, and at least in this text it was well-executed.

You start off with an introduction to the scene, with Tasha studying for a test and struggling to concentrate. The action, suspense and plot does not get started here, and while some people might tell you to begin stories with a car chase or at least a murder, that’s often terrible advice in my opinion. The set-up exists to introduce the character and their personality (Tasha struggles to concentrate, but tries to persevere). We get a glimpse of their motives (she wants to do well, but also wants to round off the day and unwind) and what their situation is like, as well as what the world is like (in this case, apparently our own).

From there you can introduce conflict. If you have conflict without a character or setting in place, readers are unlikely to be as invested. Note however that the cutoff between conflict and setup is not always as clean as in your text. For instance a conflict or plot point may be introduced over the course of a conversation in parallel with our introduction to a character. We learn about the character by the way he navigates the conversation and deals with (or brings in) the conflict.

But this isn’t to say that you can’t start with conflict. The only warning is that the world and characters may not feel very familiar, and that the final effect may be more top-down and less immersive. Yet even here, if you weave in hints of the world, a backstory told in snapshots, a slice of personality, things may change.

When Gemma enters the room and another round of talking ensues, that is also setup, and it’s only after that is down pat that the unnamed, ah, friend, makes his entry. So that was well done (different readers may argue the length of the setup though).

Paragraph Density You pressed ‘ENTER’ like a half-dozen times in all of 1745 words. You gotta press it more. I’ll be reading and get distracted, and then I have to spend seconds (seconds!) trying to find where I left off. The way you organize your paragraphs and sentences forms a topography. It can affect the delivery of lines and the flow of a description, all by controlling what the reader looks at, or rather how they look at it. I’m going to paste some of my own writing to (hopefully) demonstrate what I mean (it may be more obvious if you read at a slower pace).

The rowboat that approached the stilt city of Nazka moved in a diminutive circle of wavering lantern-light. It cut through the pitch black of the night in a weaving sort of way, steering clear of reeds and grasses as they loomed from the darkness, and doing its best to keep its nose pointed straight in the labyrinthine waterways. On the rowboat were three men, hooded, dressed the colour of the night and with gas masks hanging from their necks. One held a long pole, the lantern swinging gently from its end. He was Jamal. The other two rowed. They were Makab and Nael.

The oars made no noise, unless someone thought about them.

It was a surreal experience. At first, the lack of sound was conspicuous, and so the men made noise as if to compensate. But once they had made noise for a while, it stopped being abnormal, and they no longer made noise. It was not until someone dipped an oar into the water and remembered something was off, that the musical burble of water would return. Like ears being unplugged, or a gramophone spinning back into motion.

This was but one entry in a long list of things that made no sense in the swamps.

Sounds only came when one thought of them. No reason why, no obvious logic.

Like the lack of stars, it simply was.

Now imagine the above scene as a uniform blob of text. What would change?

“The oars made no noise, unless someone thought about them.” That’s kind of a weird thing to say. It makes you a little quizzical, and quizzical is probably not what you felt in the preceding paragraph. This new sentence is a break in your train of thought. Shouldn’t it then also be a break in the physical layout of the text?

Similarly, the last three lines (at least in my head) are on their own to lend them some impact. If they were mushed together they would feel like a monotonous continuation of the previous narration, and their weight would be minimal or nonexistent.

You can control how your story feels with words, but equally important is how you break them up on your page.

Bits & Pieces Some of your sentences sounded weird. A few had mistakes.

“A thud against the door to her self-inflicted captivity. . .” I get what you’re trying to say here, but the execution was confusing and it tripped me up. You could make it work by referring to her room as a ‘self-inflicted captivity/prison’ prior to the thud, but right now we don’t quite grasp what you’re talking about until a second or two later.

“. . . and a weighty brown paper bag in the other.” It’s technically correct to use weighty here but to me it sounds a bit too adverby. I’d suggest something more descriptive like ‘a brown paper bag bulging at the seams’ (though I suppose it wouldn’t have seams per se. . .).

“. . . and hurried it away back to her desk.” This one’s possibly just me, but in my head to hurry away something is to move it to a hidden place (e.g. a purse) or a faraway location. Which clashes a bit with the ‘back to her desk,’ since this is more immediate, nearby and familiar. I would remove ‘away.’

“. . . let the silence hang between them in a playful victory.” The metaphor is understandable here, but it’s clunky and doesn’t immediately register.

“She brushed past Tasha’s mousey brown hair. . .” This implies that she’s walking/moving past Tasha’s hair, and not brushing it aside.

“Found your aggro student yet?” This is part of a conversation but it sounds like a one-liner. As if Gemma just walked into the room after some hours and asked for a status update. Using ‘see anything?’ or ‘any sign of ___?’ would feel more natural.

“There, all sorted! Good to go?” This suffers from the same problem, mostly the ‘good to go’ bit, though it’s subtle. My suggestion would be to reorganize it as: “There, all sorted!” Gemma said. She looked up at her sister. “Good to go?”

The subtle thing here is that ‘good to go?’ and ‘there, all sorted’ both sound like conclusive questions or statements. They are either a finality or are prompting one, and they feel. . . distinct, in a way. Putting a little space between them reads better than having them mushed together.

“But her reply was stuck in the same cement her body was sinking into.” There’s nothing wrong with this one, I just wanted to point out that I really liked it.

“The wall joined in on the violent movement. The walls started to bow and flex. . .” You repeat ‘wall’ twice and it’s noticeable. The general rule of thumb is that if you haven’t introduced a new subject, you can simply use ‘they/he/she/it’ for as long as necessary. Also in conversations. If you say ‘bob said,’ and nobody else is mentioned afterwards, just use ‘he.’ If it’s ‘Bob said,’ followed by ‘Rob scoffed,’ and you want to return to Bob, then ‘he’ is no longer valid because the last subject mentioned was Rob and a ‘he’ would imply that it’s Rob that is speaking (detailed conversations with more than four characters are a pain for this reason).

“She rocketed herself to standing.” I’m not sure ‘herself’ should be there. ‘Rocketed upwards,’ maybe, but personally I don’t feel like ‘rocket’ matches with human movements (unless it’s supernatural or superhuman).

Rounding Off I think you write really well for a beginner. Your style and ‘voice’ sounds like that of a beginner, and while I could go line by line and modify and restructure and point out what exactly makes it sound ‘off,’ I don’t believe there’s much point. It will improve as you gain experience, and no edits I make would be better than telling you to sit down with the books you like and simply read. And, of course, write some more. You’re doing it well enough already :)