I think fun in learning comes mostly from the "intuition reward". If you understand and _feel_ some abstract concept in an intuitive manner, you will feel happy

I think fun in learning comes mostly from the "intuition reward". If you understand and _feel_ some abstract concept in an intuitive manner, you will feel happy and you will probably want more of that. So, for teachers finding ways to teach concepts that can trigger students intuition, in my experience as a student, will get more engaged students.