The Event B modelling language provides a framework for teaching programming methodology based on the famous pre/post-specifications, together with the refinement. We illustrate the call-as-event pattern for helping users to use Event B. As teacher, we are using students to evaluate our methodology and we give comments in italic, when we have got reactions from our students: a given definition, a concept related to our methodology, for instance. We discuss points related to our lectures at different levels of the university, mainly master. Simple case studies illustrate the teaching methodology based on interactive proofs.