1. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, La Jolla, CA 92093-0085.
2. PhD Student, Dept. of Structural Engineering, Univ. of California, Univ. of California, San Diego, La Jolla, CA 92093-0085. E-mail: mfraser@ucsd.edu
3. Evaluation director, Multimedia Education Resource for Learning and Online Teaching (MERLOT), Long Beach, CA 90840-0901.