It takes skill to learn to balance all of these tasks. Otherwise, you make more work for yourself trying to borrow notes and catch up. Plan enough time for studying The rule of thumb is three hours of total work per week for each credit you take. 15 credits means 45 hours a week of work. That means two hours of homework per hour of lecture.
Labs use more time in class and usually demand less homework.
Prepare for Classes You'll get much more from your lectures or labs if you read the text or assignments before class. Skimming the material first will familiarize you with the vocabulary and the basic concepts so that you can follow what the professor is saying. Review your notes prior to each class, then if you have any questions, you can be prepared to ask them. You need balance and perspective. Reward yourself for hard work with planned time for fun.