This is great. This is the culture of criticism we need.
I don’t know if Jason has redesigned my slides (since they’re all intact) so much as he has extended them in a particularly meaningful way. We motivated the concept of range by fixing the means, telling the kids implicitly, “you can’t use that anymore.” Now, Jason inserts this slide, which fixes the mean and the range, asking the kids, “now what can you do with this?”
This approach to skill development works both with fancy visual application problems and with skill acquisition. Rather, than 1) defining some concept like “range,” and then 2) using it in example problems, we instead 1) discover the limitations of our current tools and then 2) invent new ones. These mathematical operations didn’t arise just to employ degenerates like me. They arose because we needed them.
To the extent that Jason seems to think we should skip range altogether, I disagree. (Why not talk about it?) To the extent that he thinks we should engineer a situation where range is no longer useful, where the students must develop stronger tools like variation and standard deviation, I say nice job.