Instinctive understanding of programming constructs can vary widely from person to person. I never had any problems understanding loops - it always seemed obvio

Instinctive understanding of programming constructs can vary widely from person to person. I never had any problems understanding loops - it always seemed obvious to me. I was happily coding away in Turbo Pascal at the age of 8 with nobody but a big fat programming book to help me. On the other side, I was pair-programming with a friend during an intro to programming course in my first year of college and he just couldn't get his head around loops. He was smart and incredibly hard-working (and went on to complete two MSc in parallel). But loops, the difference between a while loop and a for loop, and programming constructs in general just didn't make sense to him. He had to work really hard to figure out how to use them. I'm sure there have been studies that explain this but I should get back to now rather than start doing some academic research....