Abstract
This research tries to use multimedia animation to design examination questions and develop a Web-based Performance Assessment system (WPA system) to evaluate examinees' understanding of the procedure of scientific experiments. WPA system also documents and scores the process an examinee responds to multimedia animation questions, including the tracks movable objects leave on the screen, and information examinees input and whether their answers are correct. Examinees' recorded process of the operation of each multimedia animation question can be replayed for teachers to grasp a full picture of examinees' process of answering. WPA system can be used for improving and evaluating students' understanding of the procedure of scientific experiments.