How many do you collect when they are young, and how long are you keeping them for? I think I have enough to fill a small filing cabinet and I am not sure which to keep and which to let go (and when)....
I say keep them all even if some of them doesn't look good or already faded. Each drawing has its own story to tell so don't throw any of them. Those drawings are like frozen time capsule wherein you can't return to those moments anymore.
At the moment I have about 100 drawings/painting form my 2 and 3 year old- mostly just scribbles. I don't want to chuck em cos each pic shows a bit of progression. But when we moved house I archived about 6 of them and threw the rest.
When you have a lot its hard to store them. So I take a photo of every drawing and then they are recycled. This way I can permanently and forever keep a copy.
I really need a place to store these as right now they are spread all over the house. I am thinking a large booklet that I can press them into, but so far I am not finding anything big enough to hold the backboard photos.
Kid Drawings 
Linear Mode
