Some of my professors at GaTech complained that half the students just "couldn't learn" computing. I believed it at the time, but now I think it's that certain styles of coding are prone to mistakes when under stress -- such as when taking a test or on a deadline to submit an assignment.
The classic example is the swap function. One professor asked us to code swap on every exam, even announcing he would in advance. Every exam, a significant portion of the students got it wrong. Because they couldn't memorize 4 lines? That's hard to believe. Easier to believe those 4 lines are so easy to remember that the student wrote them too quickly and moved on to the next question before noticing they'd written them out of order.
The classic example is the swap function. One professor asked us to code swap on every exam, even announcing he would in advance. Every exam, a significant portion of the students got it wrong. Because they couldn't memorize 4 lines? That's hard to believe. Easier to believe those 4 lines are so easy to remember that the student wrote them too quickly and moved on to the next question before noticing they'd written them out of order.