Today, most lecturers at UK universities face a diverse student body. Widening participation initiatives, the modularisation of programmes, alternative articulation routes into programmes and internationalisation have led to a diversity among the student population that can pose challenges to individual lecturers. These include a level of uncertainty over students' prior knowledge and experience relevant to a specific module. Despite controlled access to higher education (HE) and instruments to measure prior learning, the remaining differences among students can have a negative impact on teaching and learning. This workshop introduces the use of diagnostic tools, which are intended for the students to diagnose and address their weaknesses, as one possible way of responding to this challenge. It will outline the use of a diagnostic tool in a level 3 engineering module at Glasgow Caledonian University (GCU) attended by students from a range of different programmes and backgrounds. The workshop will conceptualise the different steps involved in creating this tool and will give participants the chance to begin planning such a tool for their own modules. Data gained from the evaluation of the diagnostic tool at GCU can provide insights into the specific benefits and challenges participants are likely to face in introducing such a tool to their own teaching.