Academic work is a college student's job in life. The inability to do that job can be painful and confusing to students who do not recognize that grief is affecting them. Learn about how grief affects you. Know your won limits and take time for your grief during your studies. Find ways to allow yourself time to be with your loss and seek support from those who will understand.
Some friends can offer more support than others, especially if they have lost someone themselves.
Each kind of friend is important. You may need to share with friends some of what you are going through so they can understand how you are acting. If you have intense feelings, it could be helpful to find support through counseling or support group as a way to express yourself more freely. You may find that professors are unsure about how to interact with you when you share with them you have had a death of someone close to you. Death brings up feelings that are uncomfortable for many people.