Take Proper Sleep:
The very thing you have to make sure before going to school is getting enough sleep. When you don’t have enough sleep you suffer from fatigue and lose vigilance and concentration. So it is difficult for you to stay focused. When you don’t have enough sleep mostly it becomes difficult for you to have a proper breakfast. With very little or no breakfast, your energy level decreases and you feel more sleepy. First try to have enough sleep and proper breakfast. Always keep some snacks or nuts in your bag to boost your energy level. Always keep a water bottle with yourself to keep your body appropriately hydrated. Do exercise daily. This also helps to keep you fresh even if you don’t have enough sleep.
Reduce Disturbances:
Mostly you lose focus because of the continuous message beeps on your phone. Instead of focusing on the lecture you try to search for the chances to have a look on your phone to reply to the messages or comments. Once you get busy on the phone it is rare to get back to the lecture until the teacher notices you. So the best solution is to schedule power on and power off on your mobile, so that your cell phone automatically turns off before you enter the class. Try to sit in the first or second row nearer to the teacher so that you get less chances of using a cellphone.
Participate in Discussion:
Try to take part in class discussions and question answer sessions. This will keep you concentrated and busy in thinking about questions and their answers. If you are a kind of person who doesn't speak in class and you are not confident enough to ask questions or give answers then write the questions and their probable answers in your notebook and compare them with questions and answers given by other students.
Keep Yourself Busy in Notes:
When you are not making notes during lecture, you are just listening passively, and at the end you lose the focus. So whether you think that the topic is very easy and you don’t need to take notes or the teacher will share the slides, you are actually letting yourself lose concentration. Keep yourself busy in making detailed notes. This will not only force you to concentrate but also help to remember things.
Find Motivators:
Sometimes it is toughest for you to concentrate in classes of the subject you dislike or have no interest in them. Or you have already decided to drop this subject in finals so it is not important to take class attentively. So one side you are thinking to not take lectures and on the other side, you consider it not sensible to bunk the lectures. In situations you need to search for something that motivates you.
See a Doctor:
If you still don’t get enough help to motivate you or keep yourself concentrate during lectures, you might need a medical check-up. There might be any kind of illness that is causing problems for you. It may be anxiety, depression, and anemia, weakness due to basic vitamins or minerals deficiency, or ADHD.
Before Class Aids:
Another helping way is preparing for upcoming lectures. If you know the topic or chapter to be discussed in next class do prepare for it. Search for interesting questions or any interesting example to share in next class.
Questioning:
If nothing is working for you to keep you on track then start asking yourself questions. Write down the questions and possible solutions. Then do the counter questioning. In this way you are acting as a mentor for yourself.