So, I know the basic rules of chess, but I'm terrible at the game because I've never practiced. This site looks neat!

I also spent the last two years designing curriculum to teach folks how to program. I have some issues as a student.

I'm currently on the "Sharp Pin" exercise: http://chesscademy.com/exercises/the-sharp-pin-that-piece-is...

I get the basic idea. You have a piece which can't move without exposing a more valuable piece to attack. Here's where I get confused.

There are three pieces involved in this situation: the piece you might want to move, the more valuable piece you would expose, and the piece that would attack. Let's call these pieces M, V, and A, respectively.

It's unclear when you say "X pins Y" which of M, V, and A can go into X and which can go into Y.

Now, if I'm confused about this, look at the hint: "Try pinning the knight to the king"

Pin whose knight to whose king? If I'm confused about the syntax of pinning this hint doesn't help me at all. It's all the more confusing because I'm not sure what you mean by "the" king. There are two kings on the board, right? Which is "the" king? It's worse with "the" knight, since there are four knights on the board.

Now, I spent about 15 minutes parsing out what you meant and saw what was intended. However, I started doing some no-no student things along the way. At first I tried to understand what the sentence meant. I looked at the kings and knights and tried to imagine how one would pin one to the other.

"Pin the knight to the king." Well, the king is the most valuable piece, so it's probably V in this formulation above. But is the knight the M or the A? Now I'm looking at the knights on the board, thinking about moving them around, and I don't see how any move I make could be consistent with the instructions. Hmm, ok, so the knight must be the M which means it must be one of the black knights.

You can see already how I'm not really thinking about the problem but trying to reverse-engineer what you mean. I'm doing this because I don't have a clear picture what "pinning" means in my head.

Now, when I think about moving pieces, I look at the board. What piece should I move? Well, I dunno, the pawns are out there and are near a knight. Maybe that's what pinning means? I'll move the pawns in the center and see if it yells at me. Ok, it yelled at me both times. What other piece could I move? Maybe I was wrong about knights being the M, so let's try all possible knight moves and see if the system lets me make any of those moves. Nope, ok, those are all bad.

Yikes! Now I'm just guessing and relying on your system to tell me what's right or wrong.

Ok, obviously the problem is I'm confused about WTF pinning means. How can I see some examples of pinning? I don't see anywhere on this screen. So, I go to Wikipedia and read the article on pinning. Ah, I see, "X is pinned to Y" means X can't move without exposing Y. So, maybe "Pin X to the Y" means move some piece into a position where "X is pinned to Y."

Ok, well, the knight and the king are lined up diagonally, so the only way the knight could be pinned to the king is by a bishop. Oh, look! Ok, I can move that bishop. Yay! I get the gold star.

This sequence of events is a problem on several levels.

First, most students wouldn't keep at it like I would. They also wouldn't have the self-awareness to see that their first priority is to deconstruct the ideas you're trying to express and reframe them in a way they understand themselves. They most likely wouldn't look to outside resources like Wikipedia, either, because they'd get "tunnel vision" on the current page.

Second, you confused me by talking about absolute and relative pins. I don't know whether I'm going for an absolute or relative pin in this exercise. The hint gives it away, but only by process of elimination. That is, "This must be an absolute pin because otherwise it wouldn't make sense for a king to be involved."

Third, although I eventually get the "right" answer, my path to that answer looks nothing like the path an expert would take. What hint can you give that suggests not just the proper outcome but encourages expert-like habits in the student? I don't know enough chess to suggest, but here are some ideas.

"Think about what moves your various pieces can make. Are there any avenues of attack that line up with those possible moves?"

"To pin the black knight to the black king, you need to move one of your pieces so that it is attacking the knight and would be attacking the king were it not for the knight's position."

This latter hint is nice because it also reinforces previous lessons about attacking, including the forking exercise which also involved attacking two pieces at once. Now I'm relating this current situation to a previous one, and it makes me think there might be some interesting relationships between pinning and forking.

Anyhow, just some thoughts from a guy who spends too much time thinking about curriculum and pedagogy!