The art or practice of concentration is to eliminate distraction and focus on the task at hand. If you find that you read through material and suddenly discover that you have no idea about what you've just read, or if you attend lectures and have difficulty paying attention to what is being said, these tips may help:

• Stick to a routine, efficient study schedule
• Study in a quiet environment
  
• For a study break, do something different from what you've been doing (e.g., walk around if you've been sitting), and in a different area
• Avoid daydreaming by asking yourself questions about the material as you study it
• Before lectures, look over the notes of the previous lecture and read the course material pertaining to the lecture so that you can anticipate the main ideas that the instructor will cover
• Show outward interest during lectures (attentive expression and posture) to self-motivate internal interest
• Resist distractions by sitting in front of the room away from disruptive classmates and by focusing on the instructor through listening and note taking

J. R. Hayes, The Complete Problem Solver, Franklin Institute Press, 1981