CONTEXT- Plant system engineering (PSE) is a method of efficiently integrating machinery and human labour. Studies in PSE have been mainly concerned with production facilities rather than teaching facilities. NEED - Conventional simulation methods assume the product moves through the workstations. In the more complex situation of the training workshop, both the student and the artefact being produced move through the workstations. Hence a training workshop requires a fundamentally different way of approaching the simulation. Also the waiting time experience of the students needs consideration, from a teaching perspective. APPROACH- We adapted the system simulation methodology by including multiple work-streams through the workshop, and by adding decision stages into the model. The method was applied to a training workshop. FINDINGS - The results identified specific changes in the way the students were assigned to machines, and the number of different types of machines, that would improve the operation of the facility. The improvement measures were reduction in waiting time by students, and greater machine utilisation. Multiple different class sizes were explored. IMPLICATIONS- The approach is broadly applicable to other situations where the people move through a facility along with a partially completed physical product. ORIGINALITY- This work develops an approach to optimise the performance of a manufacturing system, for the unusual class situations where the product moving through the simulation is not merely a physical product as in conventional simulation approaches, but rather the combination of people (students) and their partially completed physical product.