First, I got a large plasice container ( I love plastic containers...) for each one of my kids, Danny, Josh and Jake.
Then I made a file folder for each school year: (now I did this as they were growing up so it didn't take much time/effort, but even if your kids are older you can still make this work.)
I like to put their name, school year and a picture on the outside of each folder. Inside I keep report cards and a few samples of handwriting/math skills or an assignment they did really good (or really bad) on, and awards:
As they got older, pictures and such didn't come home much but I would try to snag copies of reports (even if it means I have to print them off after they leave for school! LOL!)
Some of my kids teachers did the work for me and sent home 3 ring binders with all the years work in it:
As the years go by, the box get's fuller and fuller and a few other trinkets get thrown in: (like Mickey Mouse ears, baby shoes, year books)
but everything is in one place, organized and each kid will get when they get married- Wait, I'm not ready to give up Danny's box- when they have kids of their own. :)
And that's what works for me!