The photos are CC BY.[1] Chronophoto, a game of guess the years of these photos, is currently on the front page.[2] So how about a similar game of guess the incomes?

Compared with historical photos, the narrower scope of dollar-street photos might be less fun? Or not - it's a richly textured image set. Deep linking the dollar-tree site could give richer follow-up context. Perhaps paired guesses of income and location, might quickly teach their relative salience?

[1] https://www.gapminder.org/dollar-street/about? [2] https://news.ycombinator.com/item?id=34559867