Performance on homework questions was compared with performance on related exam questions querying the same fact or principle, was used to assess the effect of answering online homework questions on subsequent exam performance. A distinctive pattern of performance was found for some students in which superior performance on online homework questions resulted in poorer exam performance. When assessed over an eleven-year period, for 2433 students in 12 different college lecture courses, the percent of students who did not benefit from correctly answering homework questions increased from 14% in 2008 to 55% in 2017. During the most recent two years of the study, when students were asked how they did their homework, students who benefitted from homework reported generating their own answers and students who reported copying the answers from another source did not benefit from homework.