A good example would be when people originally believed the earth was flat. With increasingly advanced technology to provide evidence it was actually spherical, that conclusion changed.
Another would be that all light is just white, but Isaac newton discovered it was a mixture of Red, Orange, Yellow, and so on.
A third would be the popular 1600s and below belief that germs weren't real. The invention of the microscopes led to cell study, and thus the belief germs indeed existed spread.