“Interpolated” is a fancy way of saying inserting something into something else. Interspersing questions throughout the video watching experience and testing students on what they’ve learned can increase engagement and improve retention.
Research shows that testing helps students learn material better than repeated review of instructional material (Roediger & Karpicke, 2006). That means you want to ask students questions about what they've learned instead of letting them rely on simply rewatching your instructional videos. Studies have also shown that embedding short quiz questions into videos increases both learner engagement with the video (Kovacs, 2016) and time spent on the learning material (Vural, 2013). These interpolated questions help students stay focused, reduce anxiety about graded exams (Szpunar, Khan, & Schacter, 2013), and avoid overconfidence (Szpunar, Jing, & Schacter, 2014).
Many learning management systems have quizzing tools built in, making inserting questions an easy task. You can also use specialized tools like HapYak and Google Forms (Brame, 2016) or EDpuzzle, Panopto, and Vizia. However, it is important to remember that practice and testing alone is less effective for learners than when you couple them with providing formative feedback. Many tools will allow you to automatically mark a student’s response correct or incorrect, and provide feedback or the correct answer. You can also use simple text pages or additional videos to provide an explanation of the correct answer and common mistakes, or provide feedback in live sessions.
Brame, C. J. (2016). Effective educational videos: Principles and guidelines for maximizing student learning from video content. CBE—Life Sciences Education, 15(4), es6. https://doi.org/10.1187/cbe.16-03-0125
Kovacs, G. (2016, April). Effects of in-video quizzes on MOOC lecture viewing. In Proceedings of the third (2016) ACM conference on Learning@ Scale (pp. 31-40). https://doi.org/10.1145/2876034.2876041
Roediger, H. L., III, & Karpicke, J. D. (2006). The power of testing memory: Basic research and implications for educational practice. Psychological Science, 1, 181–210. https://doi.org/10.1111/j.1745-6916.2006.00012.x
Szpunar, K. K., Jing, H. G., & Schacter, D. L. (2014). Overcoming overconfidence in learning from video-recorded lectures: Implications of interpolated testing for online education. Journal of Applied Research in Memory and Cognition, 3(3), 161-164. https://doi.org/10.1016/j.jarmac.2014.02.001
Szpunar, K. K., Khan, N. Y., & Schacter, D. L. (2013). Interpolated memory tests reduce mind wandering and improve learning of online lectures. Proceedings of the National Academy of Sciences of the United States of America, 110(16), 6313–6317. https://doi.org/10.1073/pnas.1221764110
Vural, O. F. (2013). The impact of a question-embedded video-based learning tool on e-learning. Educational Sciences: Theory and Practice, 13(2), 1315-1323. https://files.eric.ed.gov/fulltext/EJ1017292.pdf