I'm currently writing a script. Being as I have up until this point done extremely short shorts with friends, I've never fully scripted a longer work. I have come upon a real problem. My story revolves around a highschooler. How do I show a progression of time in his life. I.E, how do I show different experiences at school or with his friends, and make it clear the year is going by. I don't want to do a "5 days later" type thing because that isn't the film's style. Any help would be appreciated.

the most common way, is to create a visual montage....
In the cinema, the art of conveying an idea and/or mood by the rapid juxtaposition of different images and camera angles. (2) In art, the kind of work made from pictures or parts of pictures already produced and now forming a new composition. Compare assemblage, collage.

then transitioning the guy from point a in his life, to point b.

montages usually have little to no dialogue, and are usually set to music...

You could also show the passage of time through shots of different weather, shots of different times, and/or shots of your character wearing different clothes.

Or if that doesn't work, and you want your film to have a very real approach, you could put in text screens showing different dates (in a month, day, and year format, possibly) in front of your different events to show how many days have passed.

changing seasons always has the classiest feeling, in my opinion.

another idea could be some sort of object the character keeps or works on, like a plant that grows, a peice of art he's working on, etc.

Use your imagination.

Wow... we can tell JW really loves to help people....

He's soooo niiice

How about focusing on a school bulletin board --- you could have different announcements on there to signify the dates (i.e. fall dance, Christmas party, pep rallies etc.) How would your script include a school bulletin board? I dunno, maybe your main character is always going to detention and passes by it or maybe he's an aid and is the one that posts the announcements. It doesn't have to be a bulletin board, it could just be announcements hanging on the walls or something. Just an idea.