As we humans change the environment, we unavoidably change the selective pressures on other species; as a consequence, they either adapt or become extinct. Species adapting and remaining with us, in some cases is a good thing, but when it is pests adapting to pesticides and disease causing bacteria adapting to antibiotics it is not. The following article gives 12 examples of how we are influencing the evolution of species via natural selection.
Be sure kids understand that the factor we introduce, e.g. antibiotics, does not cause the mutation that makes bacteria resistant. It is that the natural population has some members that happen to have this variation of resistance. Introduction of an antibiotic kills of susceptible members of the population, the few that have natural resistance survive, reproduce, and make a new population of more resistant bacteria–over and over.
https://www.businessinsider.com/examples-of-evolution-happening-right-now-2015-2