Multi-user input over a shared display has been shown to support group process and improve performance. However, current gesturing systems for instructional collaborative tasks limit the input to experts and overlook the needs of novices in making references on a shared display. In this paper, we investigate the effects of a single-user gesturing tool on the communication between trainer and trainees in a laparoscopic surgical training. By comparing the communication structure and content between the trainings with and without the gesturing tool, we show that the communication becomes more imbalanced and the trainees become less active when using the single-user gesturing tool. Our findings highlight the needs to grant all parties the same level of access to a shared display and suggest further directions in designing a shared display for instructional collaborative tasks.