The correlation between ability and effort

One might think that students studying a subject that comes easily to them don't have to work as hard, and that the students for whom the subject is difficult are the ones who put the most work into it.

Or, one might think that when students don't do well, it must be because they don't work as hard, while students who do well must have put a lot of effort into achieving so much.

Someone I work with suggested a third hypothesis: students who do best work hardest, but it's not that the hard work is the cause of the success. Rather, when a subject comes easily for a student, that student will be inclined to put more time into that subject. When you understand the material, the time spent on it is time during which you are engaged and moving forward. When you don't understand the material, the time spent on it is time spent banging your head against a wall. It's hard to stay focused on something when you can't really get your mind wrapped around it. While time spent studying it may increase your understanding, the understanding that you achieve may quickly slip away. I find that certain topics just don't like to stick to my brain. I have a hard time getting them into my brain, and once I do get them in, they just immediately plop right out. In contrast, with other topics, any time a piece of information is floating around anywhere near me, it heads straight for my brain and embeds itself there. I don't even have to be studying the material, or even conscious of it. Some conversation happens near me that I'm not paying attention to, but somehow information from that conversation gets glued into my brain.