Get a file cabinet, and file it per year/grade.
And ALWAYS put the date on it that he made it and the school/grade/Teacher's name so that years from now, he can look back on it and know when/what grade/which Teacher/class he was in.
Scanning it takes too much time.
Just take photos of it and digitally keep it. Then you don't have to keep the actual object. Or just keep what you want.... or frame it.
There are MANY years of this.... for each grade and age your child becomes.
Now, my daughter who is 7, 'files' her own things, in her file drawer cabinets. Thus, she is learning organization and 'filing' of her own things.
Which keeps clutter off of my desk!
These are things that I do.
good luck,
Susan