The dread of every exam-taker! According to Darwinism it used to be for
survival purposes and forgetting used to be an optimization system, and
can be replicated with a hard drive... School! You made literally everything
important!
When you clearly know something yet fail to recall it. Surprisingly
common, probably due to the brain linking it to the wrong thing.
One possible thing is due to interference, where things similar become
mixed up, like mitosis and meiosis.
The solution is to basically use spaced repetition software with short
Q&A or fill-in-the-blank, like SuperMemo or Anki! It hurts to fight
against biology... due to the evil education system... but what needs to
be done, needs to be done, to fight against it, get a university, and
get a job, once and for all!
This is because I am biased to remember the times where I recall something shocking, or forget something necessary (information for exams). Human brain is a bit messy, it was adapted from Darwinism. It cannot remember everything it wants to remember, or forget everything it wants gone. This is a pitfall of idealism. Rather, as the brain usually can still remember a lot of stuff selectively, the times where something unexpected happens can be shocking.