Our chairs are about 12 years old. Our building was completely remodeled (new furniture, paint, flooring, etc) my first year of teaching. When I see pictures of other classrooms, I'm not sure I have seen many chairs like ours. They have a little handle on the back, and the backs aren't very wide, making them not real conducive to your typical "seat sack".
My first 2 years of teaching I taught third grade language arts. I had 2 sections of kids, so my homeroom kids used the desk and my afternoon class used these bags as their "desk". When I moved to K, I took the bags with me for my kiddos to store things.
Here is a picture of the bag on a chair. The bags are about 15" long. They are made from a thick fabric. Mine have the polka dot fabric on the inside with a lining between the 2 layers of fabric. A retired aide from our building made these (I spent all of my "fees" money on these my first year...we don't get that money anymore). Another kindergarten teacher had her mom make them using duck canvas. The handle is about 20" but doesn't hang that far down; that is just how long the piece of fabric is. It is sewn into the bag a little bit as well.
Below is a photo of the inside of the bag. This year my kiddos keep their home/school folder in their bags and their bag of independent reading books in there daily. In the past I've included school boxes as well, but we're using community supplies this year. I use binder clips (2) to clip their name tags to the bags.
If you have any other questions about these or other things you've seen in my room, please leave a comment!