This paper presents an architecture-based software reliability modeling tool for pedagogy and demonstrates its support for conveying learning materials to students. Software reliability is an important quality attribute. Improving this attribute early in the software life cycle is highly desirable, because it greatly reduces testing and maintenance effort later on. The architecture-based approach is for such a purpose. This tool enables students to conduct relative analyses on different architectural designs and to compute a more accurate measure once detailed information is available. It equips a GUI for architectureto-state modeling, taking into account four architectural styles. Students can incorporate additional architectural styles into this framework, and exercise different design alternatives. The GUI shows a graphical representation of software architecture, and helps students visualize the matrix construction for design changes. This tool has shortened students' learning curve, helped them understand the impact of different designs on reliability estimates, and increased their interests in other quality attributes.