Stuff you just can't grok for long...

[Robot_Arm]

@Malacandra

Actually, you’re technically right, but at risk of confusing the student with that particular nitpick. Given that no two observers on Earth can simultaneously see the Moon from more than 8000 miles apart, and the Moon is thirty times as far away, the “little bit more” amounts to just a few miles of Moon surface right at the edge, and I’d defy anyone to spot the difference without a detailed photograph and a fair bit of work with a magnifying glass.

I’m a born nitpicker, I guess. But it’s also possible to over-simplify, sometimes. I’d rather tell someone that they’re right but it’s to small to worry about than that they’re wrong.

[Mean_Mr.Mustard]

@Dr.Girlfriend

Offsides I get, it’s icing I can never get a grip on. Why it’s waved off sometimes, why sometimes it looks like icing but it’s not called… and don’t get me started on “no-touch” icing.

Icing can be waved off by the ref if, in his estimation, the player on the other team could have touched the puck (preventing the icing) before it crossed the line, but did not.

No-touch icing, if I am understanding the terminology, does not exist in the NHL (though many are campaigning for it). It is where icing is called automatically - before the puck is touched by a player. It is designed to prevent two opposite-team players racing for the puck near the end boards, a situation with a high potential for injury.
mmm

[Infovore]

The two for me are:

1. 24 hour time
   I cannot keep it straight in my head how it works. The way I deal with it is that I have memorized (due to my college classes many years ago all being on 24 hour time) a small subset of them (for example, I know instantly that 14:00 is 2:00 and 15:00 is 3:00) and go from there. So if something’s at 18:00, I just think, “Okay, 15:00 is 3:00, so 3 hours later is 6pm. Got it!”

2. Most musical theory, including sightreading
   I want so much to learn to read music, but I simply cannot do it. I’ve tried. I get it for as long as I pound it into my brain, but even then it’s slow going. And as soon as I’m away from it for awhile it goes right back out and I have to relearn it. I have never had the “aha” moment that I am sure is there somewhere, just waiting for me to discover it. On the other hand, I can play melodies by ear and I have a relatively good grasp of time (I can count pretty well even in odd time signatures).

I understand hockey things like offsides, icing, and the blueline now, because I joined a beginner league and played the game for a few years. It makes a lot more sense when you play than when you’re just watching.

[Irishman]

@phouka

Time signatures in music:

I’ve been thinking about opening a thread specifically on this topic. Why not now?

http://boards.straightdope.com/sdmb/showthread.php?p=15132967#post15132967

[Rysto]

@Mean_Mr.Mustard

Icing can be waved off by the ref if, in his estimation, the player on the other team could have touched the puck (preventing the icing) before it crossed the line, but did not.

There’s a newer, stupider rule that comes into play here. The short version is that if, in the opinion of the linesman, the icing was a result of an attempted pass, he can wave it off.

The stupid part is how subjective it is, and it basically boils down to teams that are generally perceived as being better teams get their icings waved off way more often than teams that are expected to suck.