Peer Instruction: Turning a lecture into a seminar, at Physics Colloquium, University of California San Diego (San Diego, CA), Thursday, May 6, 1999:
    Education is more than just transfer of information, yet that is mostly what happens in large introductory courses - instructors present material (even though this material might be readily available in printed form) and students take down as many notes as they can. This format tends to reinforce the idea that learning is about acquiring information rather than gaining new ways of thinking. In fields such as physics, in which learning consists primarily of developing new thinking skills, this is disastrous. Students get frustrated because their study strategies are inappropriate, and thus... Read more about Peer Instruction: Turning a lecture into a seminar
    Black silicon: changing structure and properties with light, at Physics Colloquium, Haverford College (Haverford, PA), Monday, March 1, 2004:
    Shining intense, ultrashort laser pulses on the surface of a crystalline silicon wafer changes its structure and properties dramatically: the formerly smooth, highly reflective surface becomes covered with a forest of sharp microspikes. This microstructured surface is highly absorbing even at wavelengths to which the original wafer is transparent. This talk will describe the properties of this microstructured surface and discuss why the microspikes form and what is responsible for the change in optical properties.