A key goal of our research is to introduce an approach that involves at the outset using analytical reasoning as a method for developing high quality software. This paper summarizes our experiences in introducing mathematical reasoning and formal specification-based development using a web-integrated environment in an undergraduate software engineering course at two institutions at different levels, with the goal that they will serve as models for other educators. At Alabama, the reasoning topics are introduced over a two-week period and are followed by a project. At Clemson, the topics are covered in more depth over a five-week period and are followed by specification-based software development and reasoning assignments. The courses and project assignments have been offered for multiple semesters. Evaluation of student performance indicates that the learning goals were met.