I have problems drawing at huge sizes too, but gridding should help. Plan out your drawing in a thumbnail first, and when working on the actual drawing, step back every once in a while to check for errors.
It's not absolutely necessary IMO, but it'll help you learn to use your whole arm to draw instead of just your wrist.
It's something that is very hard to get used to. I'm actually working on something life size at the moment and you learn ( eventually) to step back a lot, measure more, and take into account that people will view it more from a distance.
"A drawing is not necessarily academic because it is thorough, but only because it is dead. Neither is a drawing necessarily academic because it is done in what is called a conventional style, any more than it is good because it is done in an unconventional style. The test is whether it has life and conveys genuine feeling."- Harold Speed [[Sketchbook]]
It's easy if you forget about moving your fingers - and work with your elbow and shoulder. Feels entirely natural after a very short time. Use the whole arm. Your hand is only for gripping the pencil or coal.
As for necessary - you bet. In fact, it is a splendid thing your art teacher wants you to do. It breaks you out of all silly little habits you might have accumulated, and gets you actually drawing. You will never draw at small sizes the same way either, after you're through this course.
...Any tips on how to become better suited for this? Is it important you draw at this size?
It's only important depending on the results you're trying to get (and making your teacher happy.) For certain things, a larger size is an advantage, but it doesn't have to be gigantic. That isn't to say that it's always necessary to go big, or that you have to draw larger to make the work better. There are tons of great drawings that are much smaller than 3 feet.
It also depends on the tool you're using. The size of the mark it makes will dictate the best size to draw on when making them. I would probably not choose a fine point pen for drawing on a 3 foot surface, but then a fat chunk of charcoal on a letter sized sheet of paper wouldn't be my first choice either. Subject matter is also involved. A sight-size coffee cup is not going to be 3 feet tall.
If this is a short term exercise from your teacher to work large, then fine, but if they're expecting you to always work that way, it's going to present more problems than it's worth. Personally, I think it's easier to translate smaller marks to larger ones than larger to smaller. Also, I like to rotate the page when I draw. I wouldn't want to try that with a giant sheet, unless it's on the floor or something.
Thanks everyone for replying and giving me helpful tips.
@dbclemons The teacher wants us to continue to work at this size for the rest of the class. Also, talking with students from the classes he teaches beyond mine, the sizes just gets larger and larger. We tape the drawings on a flat drawing board so I guess I rotation could work but it would be really annoying.
Once you get use too drawing in that size it'll become second nature. You will notice you can add alot more detail too your work, especially if you're into photo realism. You just have too be careful to not overwork the piece. The ease of which you learn this also depends on what medium you're working in, it's alot quicker too adapt if you're working in charcoal than with pencil.