Seth Godin clearly explains the difference between school and learning.

School was the big thing for a long time. School is tests and credits and notetaking and meeting standards. Learning, on the other hand, is ‘getting it’. It’s the conceptual breakthrough that permits the student to understand it then move on to something else. Learning doesn’t care about workbooks or long checklists.

For a while, smart people thought that school was organized to encourage learning. For a long time, though, people in the know have realized that they are fundamentally different activities.

Godin’s focus is on “higher” education (usually meaning college but sometimes I’m not sure the adjective applies) but his thoughts could just as well be applied to K12.