In teaching oral communications, a comprehensive (written) exam is not a true litmus test of how much a student has learned. In oral comm, what does matter is how much they have progressed in making a speech before their fellow students. Are they better than when they started? Do they make the appropriate eye contact? Posture? Is their voice loud and clear when speaking? This is tested throughout the semester and a final speech is the hope of that the "growth pattern" shown throughout the semester in making various speeches (mistakes and all) will come to full maturity.