This model may look ridiculous, but
we often behave as we believe it!
Students fail to be able to recognize the use of a physical
principle in an exam question, so we rephrase the question so as
to give “keywords” or “triggers”.  Almost all students can now
respond correctly, so we are satisfied.
In designing a computer-based homework system, problems #1
and #5 use the same physical ideas.  When starting the HW, the
student does #1 incorrectly.  Returning to the assignment on the
next day, she does #5 correctly.  Should we now have the
computer give her credit for both?  After all, by the next day
“she learned the principle”.  (What if the situation had been