The overheard conversation covered what was meant by the word 'bigger', whether it means more positive or whather it means larger and what that would mean in the context of negative numbers.
The students also covered the contexts that I posted earlier in this thread - they agreed that, in some cases -10 was the same size as 10 but that 10 was always more positive than -10. There was a lot of reasoning, example and counter-examples
What I found really interesting was that there was very little teacher input and that the students spent a lot of time pushing themselves. I've written before about keeping students 'on the edge of their thinking' (a phrase used in some Strategy materials) and what I saw and heard was, I think, a perfect example of that. At the end of the lesson one of the students walked past me and said "that was really confusing - but in a good way"
Let me know if you ask some students - I'd be really interested in hearing what they say.
What do others think - which is 'bigger'?