The aim of this review was to analyze the effects of instance response systems or clickers on students' learning in different teaching strategies. A total of 128 empirical studies were reviewed; 80% of the studies were conducted in the context of lectures or collaborative learning. Further analysis of the studies using a quasi-experimental design revealed that clicker usage in traditional lectures may enhance students' attention and participation. However, it is not more effective than low-technology methods such as hand raising or response cards in terms of learning performance. Clickers combined with collaborative peer-aided learning have shown positive results with large effect sizes. Furthermore, incorporating clickers into innovative teaching strategies appears to be promising. Finally, the use of clickers to promote high-order thinking is discussed.