For the past 2 years I have been using the BEST homework folders. They are so simple, and hold so much!
They are a little pricey, but worth every penny. They last the whole year, don't take up much space (I keep them in a locker crate), and are washable. There are two plastic sleeves inside and pockets on the inside and outside of the covers. I can put my weekly letter, homework, any new info, info to review, their behavior calendar, and work to send home inside. A very good investment.
At my school the Kindergarten, as a grade level, uses these folders. I have yellow, another class has red, another has blue, etc. We have even started the 1st grade using them this coming year because they are so awesome! Students take these home every night and bring them back everyday. They MUST bring them back everyday with behavior calendar still inside. Keeps everything nice and organized.