Faculty rely on quizzes for a couple of reasons. They motivate most students to keep up with their class work and, if they're unannounced, they motivate most students to show up regularly for class. The research on testing offers another reason, something called “the testing effect,” described as “the phenomenon in which people appear to retain more information about a topic if they are tested on that topic and engage in memory retrieval of topic information than if they simply reread or study that information.” (p. 174) It's the idea behind practice tests. If you've retrieved the information once that increases the chance that you can retrieve it again. So, if students do practice exams, their scores on the real exams improve. The caveat: most students aren't terribly motivated to do practice exams. They'll carefully review old exams and memorize the answers to those specific questions but that's very different than retrieving recently learned content.
And there's another caveat, and it has to do with student anxiety. Quiz questions promote the kind of retrieval that results in what's called test-enhanced learning. If the exam contains questions about content that appeared in quiz questions, students are more likely to get the exam question correct than students who haven't seen the material in a test question format. The problem is test anxiety and unannounced quizzes promote a lot of anxiety in some students. Those students aren't focusing on the quiz questions, they are feeling worried, unprepared, angry and otherwise disgruntled. As a result they don't do well on the pop quiz itself and they don't reap the benefits of test-enhanced learning.
Psychology Professor Khanna wondered if ungraded pop quizzes could be used to promote test-enhanced learning for all students. She explored a number of research questions related to this issue. “First, do students retain more course information if they take periodic in-class pop quizzes through the semester than if they do not take such quizzes? Second, do students experience test-enhanced learning when completing graded and ungraded quizzes? Finally, I am interested in knowing how students feel about having quizzes in their courses and if those feelings differ depending upon whether or not the quizzes are graded?” (p. 175)
She answered these questions by looking at cumulative final exam performance in three sections of an introductory psychology course and responses to a questionnaire about quizzes. In one section there were no quizzes. In the second there were six unannounced graded quizzes, and in the third section there were the same six unannounced quizzes, but they weren't graded. Each quiz contained five multiple-choice questions and students in the quiz sections answered a six question survey about quizzes.
As for results, the ungraded quizzes led to higher scores on the final than the graded quizzes and no quizzes. “The effect of [the] quiz condition can account for a grade level change in a students' final exam performance.” (p. 177) Khanna believes, “the key to successful active retrieval practice is to ensure that students are focused on memory retrieval practice and not on emotional regulation related to test anxiety.” (p. 178) Further evidence of the effects of test anxiety can be seen in student responses to the survey questions about the quizzes. “I was glad that quizzes were included in this course” generated a 5.07 mean response (on a 9 point Likert scale with 9 being strongly agree) in the graded quiz section and 6.40 response in the ungraded section. “The inclusion of quizzes in this course made me feel anxious about the course as compared to if there had been no quizzes” was scored 6.29 in the graded quiz section and 2.96 in the ungraded section.
However, other responses from students in the ungraded quiz section show that using quizzes this way does not solve attendance or preparation problems. Ungraded quizzes did not lead students to increase their study time nor did they improve class attendance. Could a solution be a combination of graded and ungraded quizzes?
Reference: Khanna, M. M., (2015). Ungraded pop quizzes: Test-enhanced learning without all the anxiety. Teaching of Psychology, 42 (2), 174-178.