Very sad to happen in the practice area. Whenever ATC informs us of another airplane that is in the practice area, I just can't help but constantly look for traffic. I get extremely uncomfortable...I hope that incidents like this could be avoided and each of us have a personal responsibility to constantly look out and make a simple radio call. Safety comes first. It makes me feel very sad for those who lost their lives. As a student who has not much experience, I feel that there is a LOT of responsibility for pilots to do everything they can to avoid mid-air collisions. Early on we students must work on safety management, not just maneuvering the machine.