Teaching Model of Da Vinci's Tank

This was created for 7th Grade History students learning about Renaissance inventors.
Students first studied his images and were asked to comment on the feasibility of building and using this tank.
They were then put in teams of 4 and given a half-built model. They were asked to finish assembling it and then asked about feasibility and function again.
Initially most students thought it could be built and work but the physical model made them question design (he'd drawn the gearing wrong), size (in order to fit people and guns inside it would have to be huge and heavy), etc.
This model enabled a rich and engaging dialog about da Vinci and his ideas.