The web-based formative assessment developed in this research is named Formative Assessment Module of the Web-based Assessment and Test Analysis System (FAM-WATA). FAM-WATA is a multiple-choice web-based formative assessment module containing six effective strategies: 'repeat the test', 'correct answers are not given', 'query scores', 'ask questions', 'monitor answering history', and 'all pass and then reward'. This research explored the effectiveness of FAM-WATA, cognitive styles and e-learning, and student attitudes towards the six strategies of FAM-WATA. A total of 503 seventh-grade students in central Taiwan were valid in this research. Overall results indicated that students displayed a positive attitude towards the six strategies of FAM-WATA. In addition, results also showed that students in an e-learning environment equipped with FAM-WATA achieved better learning effectiveness, and that field independent students appeared to make better use of FAM-WATA strategies than field dependent students. This research concluded that FAM-WATA benefited student learning in an e-learning environment.