Create a paper prototype of your user interface design. You can fix any problems that you have identified since you completed Assignments 2 and 3.
Since this is a low-fidelity prototype, do not spend a lot of time making the interface look perfect. It is more important to simulate some of the main operations. You should be able to use the prototype to explain to a user or developer how to complete various tasks in the interface.
Then, perform a live evaluation of your paper prototype with someone outside your team as the subject (you can do this in class or later as homework).
Have the person perform a few simple tasks; these could be the same ones you analyzed in Assignment 3. The outside person serves as the test subject (performing the scenarios), while one of the team members simulates the actions of the system (placing/removing the appropriate paper screens).
This evaluation will be more informal than your future usability test. Use your low-fidelity prototype to communicate your design ideas to your subject. Have the subject go through some of the tasks in the system, using the "think aloud" method. Report any difficulties your subject had while completing the tasks, what characteristics they liked, what characteristics they did not like, what was easy or difficult for them, and what you think would need to be improved.
You will find some resources for this kind of prototyping on the course web page. You can also see the following examples for simulating and testing a paper prototype: