This happened some time ago when I was in high school, so I apologize for being vague. There are some things that are a little hazy, and I'll be happy to clarify if I can. Sorry, I can't add flair for Weekly Topic.

I was diagnosed with a learning disability at an early age, and I'm lucky to have had the support in school I did in order to learn to work with it. However, I still struggled in areas like math and science. This lead to me being in a 'less challenging' math class, and not being in the same science classes as my peers. I was taking math and science classes with the grade below me, which I found kind of shameful, and gave me a poor work ethic and bad attitude towards those classes.

In chemistry, we were assigned a large project. It was a lot of busy work, but we had a fair amount of time to do it. I was actually pretty proud of myself for actually budgeting my time, and getting everything done with minimal stress. However, that didn't really matter for long. Someone in another class had plagiarized their assignment, so unless something happened, this whole ordeal just wouldn't be counted for anything.

As previously mentioned,I was taking math and science classes with a similar group of people. There was one boy who I had grown to dislike due to his loud and disruptive nature. I already hated this class and was having trouble in it, and having him behind me, constantly making noise didn't help.
One day, he made the mistake of outright saying he had bought his finished project for chemistry off another student. After mulling it over, I decided to write a letter to the chemistry teacher, advising him to what I had heard. I was hoping he would get in trouble and I wouldn't have to deal with him for a while. The teacher reacted to that information, giving the relevant individuals failing grades. I didn't get rid of him as long as I would have liked, but I was never suspected.

TL;DR: Despite struggling, I did work worth being proud of. When a student I had previously developed a dislike for openly admitted to buying a finished project off someone, I snitched because I didn't learn time management for nothing, and I wanted him gone.