Watching your talks, what a great piece of advice mk. Was there anything beyond the "um's" that you noticed while watching it? Did it change how you perceive your mannerisms when talking? I find that I'm more engaged when someone effectively uses hand gestures/body language when speaking. It tends to show me that they're more engaged. I like the idea of communicating ideas through stories. When making presentations, I will often try to use stories or metaphor to communicate a complex idea, to make something that seemed undesirable seem attainable and attractive. This has taken years to get good at. I will also try to challenge assumptions, nothing gets your audience captivated like being challenged. Good luck with your talk, it sounds like a cool moment in your professional development. The student has become the master! Try not to laugh uncontrollably ;-)