This is a tough one in our environment with constant distractions, but let me take a shot...
- Meditate! I just finished a grad program and meditation helped me greatly in focusing on my studies. A short practice 10 minutes before studying worked wonders.
- Set a timer! Say you want to focus on reading or studying for a particular class for 30 minutes. Set a timer and stick with it. Reward yourself after with a bit of chocolate or a walk or whatever works for you after.
- Put your phone in DND mode. It can be so tempting to want to respond or react to every ding - status updates, text messages, etc. There are great apps you can use like Forest to help you with this. This particular app 'plants a tree' for a set amount of time on your phone and if you touch your phone before the time is up the tree dies. I've found it quite motivating.
- Prioritize. There are weeks that you won't get it all done. You'll have easy classes and hard classes. Sometimes you might have to skip the reading in the easy classes. Focus on assignments that need to be handed in and graded. But don't forget that the intention always is to learn.
Good luck and let me know if I can help you further!