Progression in evidential understanding

You have a wealth of fascinating sources you would love to explore with students but despair at their seeming inability to connect ‘source work' with the construction of historical claims. Year 7 get stuck in the ‘it's biased so we can never know' trap again and again. Year 9 students never get beyond ‘stock' comments such as ‘it was written at the time so it must be reliable.' You suspect that a few of your Year 11 pupils think that ‘inference' is a skin condition.

How can you help pupils to see source material as a source of evidence that can be used to construct or evaluate a historical claim? In short, how do we help pupils make the connection between ‘source work' and ‘evidential understanding'? And what does progression in evidential understanding even look like?