You CAN concentrate; you are just choosing to let your mind wander elsewhere.

Since this work isn't important to you, that's why you are choosing to do other stuff. Figure out a good reason to finish this and focus on that to get stuff done each day.

You said you have a huge book of grammar to finish: figure out how many pages or sections you have left and divide it by the number of days left until school. That will tell you how much you should finish each day.

Then, find an uncomfortable place to work: a hard chair at a table or desk, for example. You want it uncomfortable (or at least not cozy) for two reasons: 1) you're less likely to want to stay in that spot than elsewhere, so you'll focus more to get off that chair; 2) because it's not cozy, you're less likely to have your mind wander or get drowsy, which means you'll be more alert to stay focused on your work.

Another thing to do: use a timer. Make yourself finish a certain amount of work within a certain amount of time. If you really goof on how much you can get done, then adjust as needed.

Yet anoterh thing: work comes first. Don't allow yourself to do ANYTHING else until you've finished your allotted work for the day.

One last thing: don't say "I can't". Yes, you can. You may not want to, it may be difficult, it may be frustrating, but you CAN. Just repeat in your mind over and over things to keep you on task, "Work first, play later; work first, play later," or whatever else you might come up with. It helps.

__________________
I Love Yahoo! Answers