Elementary: I can't remember very much. I know I wasn't very popular, what with being the weird fat kid.
Middle School: I absolutely hated it in the beginning. Our middle school merges two elementary schools, so half of my class was entirely new to me. The closest things I had to friends left me in the dust, and I was ridiculed constantly (again, for being chubby and weird). I couldn't even read a book in peace. I tried, and a few people just came over to play keep away with it, ruining the spine in the process.
There's actually one particular incident that still angers me to think about: I was going outside for our fifteen minute recess, and was the last person on my way out, because I was slow to finish packing my things up after class. When I tried to open the door, a large group of people from my class decided to stop whatever they were doing at the time and pin the door shut so I couldn't come out. I pushed, but it eventually got so humiliating that I just went back to the classroom. I told the teacher about what happened and rather than do anything, she had to struggle not to laugh (all of my teachers weren't this terrible, it was just this one in particular).
Thankfully, I started to make some friends around the start of 7th grade, and things generally got better. I was still a bit flabby and was considered to be weird, but I was willing to take what I could get.
High School: I'll be starting my junior year when summer is over, and so far it's been absolutely fucking fantastic. Yes, I'm serious. Things are practically the complete opposite of how they were in middle school. Oddly, I'm one of the more popular people in my school, to people in my class, and the upper / lower classes (I'm still not eager to be chummy with those who tormented me in middle school, but I get along with them well enough. At least now I can tell them to piss off in a myriad of ways disguised as "friendly banter"). I'm actually in good physical condition now, and many of my eccentricities have either mellowed out or are now considered charming. It felt so great when I was finally able to read a book without being harassed. I get along well with all of my teachers, even the principal and phys. ed. teacher, both of whom are known for being hard-asses. I've got plenty of friends now, but thankfully, I've found a small group that I can regard as the truest sort of friends.
As far as grades go, they've always been good. My sophomore year, I managed to pull a 4.0 grade average for all four quarters, after coming so close for years.