It's decent, but it does need a little working up. The basic plot and setup is good. I would give the exposition a little more time, it feels slightly rushed as is. But don't worry, I had all these issues [and a lot more] when I was starting writing. Don't be discouraged, your writing style has a lot of promise. Give it some time and defiantly a lot of practice, and you'll be an amazing writer. :) (That sounds like I'm saying you're bad and YOU NEED TO WORK ON YOUR STUFF BECAUSE GOSH IT'S JUST SIMPLY AWFUL AS IS-no. That's not what I'm saying. Anyone can improve with time and practice, and I'm just passing on the memo :])
My biggest tip is to...I dunno. Beef it up a bit? If that makes sense? Your narrative is going pretty well, but now you need to focus some on your detailing. Body language, character profiling, and simple details serve to make reading any store a lot more enjoyable. Here's an example. I'm using what you wrote for your first chapter, and re-writing it as if I were the author. This is my style and my preferences. You need not, and should not have to follow every exact thing I say-you need to keep your individual style.
I shrugged by backpack up around my shoulders, wincing as the straps pressed against the fresh bruises on my arms. Luckily I was almost home when it started to pour, but as my wet pant cuffs clumped soggily around my ankles, I groaned. Just my luck. After being beat up by school bullies, my day had gone from a decent 7.5 to a 0 real fast. Teachers were irritable, students a little less forgiving, food a cut below the typical bland nourishment. The whole school seemed to sense the oncoming storm, and the mood certainly reflected it. As my backpack thumped against my back with every step, and my feet splashed through the gutter, I winced and fixed my eyes on my house just a few minutes away. The sooner I made it home, the sooner I could start on all the homework. In addition to my already heavy workload, the boys who had been making my life so miserable had dumped all of their work on me as well. Comply and do all their work for them meant a few days under the radar until they remembered to torture me again, refusal meant...well... I reached up and rubbed a particularly tender area on my upper arm.
Stepping through the doorway, I dropped my bag with a solid thunk. Pulling my sleeves down over my upper arms, I staggered into the hallway. My dad was stressed enough already without having to worry about my problems. Finding him in the kitchen making dinner, I paused briefly in the doorway. He looked up, a smudge of floor across his cheek. Brows knitted, he studied my face.
"Robby, you're home late again."
"Yeah, I'm sorry about that...I was just..." My voice trailed off as I desperately groped around for some excuse to explain my late apperence. Dad sighed, and I quickly changed the topic. "Er...what's for dinner?"
Despite my dejected mood, my stomach growled audibly. As my dad laughed softly, I cracked a weak smile.
"Yeah, anyways. I'll er...be in my room for a while. See you at dinner" I turned, and ran up the stairs. How long could I keep this up?
I've had more practice than you, so I will defiantly write differently. However, I hope that some of this will help you in some way. Just remember, every time a new character speaks, start a new line. Keep it up, you're doing great! I'm excited to see what you come up with next. :)