I'm a college student who finds it very easy to be distracted.

List your distractions, get rid of them.

• Use the bare minimum on your desk that's necessary for note taking, do not use your cell phone at all.

• Remove any distraction from your view by simply sitting in the front of the class.

• Sometimes, it's better to not sit next to your friends during lessons where it's hard to follow.

One important sentence missed means I'll have trouble understanding the rest of the class.

Now that you are rid of the distractions, focus.

• Make sure that you have had good sleep, if you have sleeping problems you should contact a doctor.

• Make sure that you are healthy and energetic, good nutrition and sports can help you.

• Get used to writing while listening, you can practice this at home by listening to a podcast.

• If you can't do both at a moment, focus on the course guide. Most often this is what the teacher is telling you, you'd rather want to be behind on taking notes from what the teacher is writing down than skipping an important sentence that she is saying.

  It's easier to ask something about what she wrote down and is right in front of your eyes than to ask something about what she said and you haven't heard.

• If the person next to you is annoying you, tell him that you are trying to focus.

Most of the classes last for 2 hours or longer with no intervals, except between classes.

Contact the student administration, ask for a pause in the middle.

• Really, 2 hours is a lot. You should ask if your college can have a 10 min pause; our college does.

• If not possible; the teachers should at least recap the end of last lesson in the next lesson, so you get reminded of the part where you had less focus on. This allows you to be able to follow the next lesson.

I have to study a lot harder trying to get information from recorded classes and complete them by reading books.

Focus on learning parts that you don't understand, make sure you understand dependencies.

• You seem to already study a lot harder, which is a good thing.

• If you can't learn a part that you don't understand properly, ask for help.

Try to find out the contents of a class beforehand and read the slides or book chapters. This makes you prepared for the content to come and you might even have questions ready that you can get answered. In any case, being prepared helps with losing focus when you miss a sentence or two -- you already know what the class is about.

Just taking notes can help a lot with focusing. I think this is quickies simple thing to try :).

Also: if the subject seems to be boring: Take some time at home, do some research to find how this can help reaching your own goals.

See if you can video tape the lectures. My school has lecture videos for most classes in my major, and it helps to break down the lectures into manageable sections and watch on my own time. Also I have exactly what the instructor said available when I'm studying. It helps if you write down the time of the video in your notes (e.g. 2:13 Intro to recursive backtracking).