Diagnosing students' algebra errors on the Web

Electronic Homework was an intelligent tutoring system that runs on stand-alone computers initially and is now migrated to the Web to provide an on-line homework tutorial. The system contains a database of different sets of algebra problems from which learners can choose what sort of problems to practice. When a learner is solving a problem, the system diagnoses concurrently every step he/she does, and prompts and guides him/her back to the correct solution path once errors are detected (Lee & Heyworth, 1997; Lee, 2001 (two papers)). Besides giving online tutorials, the system serves to collect students' errors for later analyses in order that the system can be improved (Lee & Heyworth, 1999).