When students watch educational videos, a teacher might ask them questions afterwards to ensure if they properly understood the content and learned from it. It might also be useful to ask questions before students watch a video. For example, maybe this helps them to pay more attention to the most important content? However, one of the worries is that these pre-questions might enhance learning about the content which are covered by the questions, but reduce learning form the other non-questioned content. A recent study by Carpenter and Toftness (2016) shows that asking pre-questions enhances how much students learn from videos, even about the sections they were not asked questions about.
"Asking students questions about what they are learning can significantly enhance their memory for that information. One specific way to do this is through prequestions—posing questions to students about to-be-learned material before they have learned it. Research has shown that prequestions prior to a reading assignment can enhance the amount of information that students remember from that reading. Unfortunately however, there is some evidence that prequestions may impair memory for sections of the reading that were not relevant to the prequestions, possibly because students attend more to sections of the passage that are relevant to the prequestions and could skip sections that are not relevant. In the current study, we explored the influence of prequestions on learning from video presentations, where such a strategy would be less likely due to the fact that the content and timing of videos are not learner-paced. Students viewed a brief educational video about the history of Easter Island. Some students answered two questions prior to viewing each of three segments of the video (the Prequestion Group), and others viewed the same video but did not answer prequestions (the Control Group). On a later test over all of the information from the video, the Prequestion Group performed higher than the Control Group. The Prequestion Group had better memory than the Control Group for information that was previously prequestioned, as well as for information from the video that was not prequestioned. These results suggest that prequestions are an effective tool for enhancing learning from relatively brief video presentations, without any harmful effects on non-prequestioned information, raising the possibility that they could be adapted for educational purposes to improve learning from videos or lecture presentations." (Carpenter & Toftness, 2016)
Carpenter, S. K., & Toftness, A.R. The Effect of Prequestions on Learning from Video Presentations. Journal of Applied Research in Memory and Cognition (2016), http://dx.doi.org/10.1016/j.jarmac.2016.07.014