I agree with Narf...teenage years are hell, lol.
There are fun times but high school and I never got along. I also agree that bad grades aren't always the result of pot smoking. I was on the honour roll in my last two years of high school, all the while smoking weed. I'm now almost finished university, and I get good grades and smoke as I please.
The problem for my lack of paying attention, or lack of interest in high school was the getting up super early, going there and you can't leave until THEY say so...and you have to do what THEY say. There isn't much room for individual thought and expression, and I think if there was, more teens wouldn't think of it as such of a death sentence. Personally, I felt imprisoned in school....just fucking hated it.

This is where I think you did well; it's important to do your school work before you get all blazed. Using it as a reward after has always worked for me.

That said, kudos to you for not snitching. If I were in that position i would be hella pissed if you just ratted on me...anyone would. All anyone wants is to be treated fairly.