It may be too complex an undertaking, but could we perhaps suggest in the comment fields below ideas that would allow us to define together what the term “progress” means in a comprehensible input classroom? Our definition should of course align with what the research suggests, and so of course it would not reflect the kinds of things that traditional teachers call progress, like preparing students for an end-of-year common test on which students each score differently depending on what color they are.
The reason this might be too big an undertaking for us is that, according to the research, language acquisition is (1) an unconscious process and is therefore completely impossible to measure, and (2) happens in different people at different rates in an order that we can neither predict nor measure (as per Krashen’s Natural Order Hypothesis).
So how do we as a group define progress? Maybe if each person defined what THEY call progress it would give us a starting point. I’ll start. My own definition is “when students enjoy learning the language and show an interest in learning more.” (That is not intended to be snarky. It is how I think after forty years in the field.)