Final answer:
Hans Rosling's students were mistaken because of outdated worldviews shaped by education system flaws that didn't promote critical thinking, and were influenced by social pressures and cognitive biases.
Step-by-step explanation:
According to Hans Rosling, his students were wrong because they held preconceived notions that were based on outdated information, leading to a worldview that was far more negative than the current reality. This misconception was, in part, perpetuated by the lack of critical thinking emphasized in the education system, which Rosling, among others, believed to be a flaw within the structure of education itself, rather than just a matter of financial resources. The influence of standardized tests on a student's ability to observe and interpret data was also cited as a limiting factor in their development of critical learning skills.
Additional contributing factors to incorrect student beliefs were highlighted as the influence of social pressures, as in Asch's 1956 study, and cognitive biases, such as those demonstrated in the quizmaster study, where individuals disregarded situational context and overestimated a questioner's knowledge.