A few years ago I taught a physics class for 6th graders at a school with an accelerated curriculum. These students are good at memorizing, and following procedures, so I was able to teach them the standard rules for deciding how many significant figures to include fairly easily, but I struggled to convey the underlying principles of uncertainty and scientific communication. I tried a few different approaches, but none of them really seemed to stick. Rather than teaching the rote memorization of rules, I'd like to be able to teach the underlying concepts and principles, and how the rules are applications of those principles. Does anyone have ideas for how to explain significant figure rules in light of underlying uncertainty in a way that a (very smart) 6th grader could understand?
Ideally, I would prefer a method that follows the principles of Modeling Instruction.