Do you go through their backpacks on a daily basis?
Do you wait until the end of the week?
Or, have you tried this technique? Give them the responsibility of giving you all of their important papers from school ( age appropriate of course).
I recommend all document from school are reviewed daily. This will allow for time to put important dates on your calendar and allow you to meet important deadlines.
Now your son or daughter will not be upset because he or she does not have the signed permission slip needed to attend the end of the school year class trip!
-So go through those backpacks daily
-Return your paperwork on time