How does one go about shirking work?

I come from Caltech, the land of "They don't take attendance - just get someone else to turn in your set for you and you're good," so I'm not sure how this stuff works in reasonable places and with grad students. But. What's the standard policy for missing class? How much advance notice do you give? Is it totally unreasonable to want to take three days off (not now, obviously, but about seven months from now) to go to a crazy awesome convention? Actually, looking at flight possibilities again, it would only be two days - the Friday and Monday surrounding a weekend. Is that a completely boneheaded thing to want, or am I entitled to a bit of personal indulgence? Augh, the conscience! It weighs!

How does one go about shirking work?

I come from Caltech, the land of "They don't take attendance - just get someone else to turn in your set for you and you're good," so I'm not sure how this stuff works in reasonable places and with grad students. But. What's the standard policy for missing class? How much advance notice do you give? Is it totally unreasonable to want to take three days off (not now, obviously, but about seven months from now) to go to a crazy awesome convention? Actually, looking at flight possibilities again, it would only be two days - the Friday and Monday surrounding a weekend. Is that a completely boneheaded thing to want, or am I entitled to a bit of personal indulgence? Augh, the conscience! It weighs!