What can you infer from this example? and Who is Right? are two modules that address issues of mathematical content knowledge and pedagogical content knowledge for teaching reasoning and proving.Each module intends to help users strengthen their content knowledge related to logical aspects of proving. It also addresses pedagogical aspects, such as students' conceptions of proving and pedagogical practices for supporting students' engagement with argumentation and proving.The modules can be used by prospective secondary teachers and by practicing teachers who seek to enhance their mathematical knowledge for teaching argumentation and proving.