The flipped classroom has gained popularity in the last decade in a wide variety of academic settings partially because of the increasing number of technologies developed that make out-of-classroom content creation easier and the need to adapt to millennial learning preferences (Roehl et al., 2013). Equally significant, there is consistent emerging evidence that supports the use of the flipped classroom because it improved students’ performance and perceptions of science (Watkins & Mazur, 2013; Tune et al., 2013).What exactly is a flipped classroom? The flipped classroom has been defined as an educational pedagogy consisting of two parts: online-based individual instruction outside the classroom and active learning activities inside the classroom (Bishop & Verleger, 2013). The online-based instruction can be designed in a format where students are provided with a variety of tools to gain first exposure to lesson material outside of class: textbook readings, mini-lecture videos, and printable PowerPoint slides.

Bergmann and Sams, who pioneered the flipped classroom approach, suggested that its gains include the development of lifelong learners, enhanced engagement with lesson material, and increased interaction between students and faculty (2012). In 2012, the majority of pharmacy students who responded recognized the convenience and pedagogical benefits of the flipped classroom model and that class attendance improved when it was applied to basic pharmaceutics courses (Pierce & Fox, 2012; McLaughlin et al., 2014). The beneficial features of the flipped classroom are plenty and include its ability to help students correct misconceptions and organize their new knowledge, provide an opportunity for students to gain first exposure to lesson material prior to class, provide an incentive for students to prepare for class, provide a mechanism to assess student understanding, and provide in-class activities that focus on higher- level cognitive activities.

Eric Mazur’s peer instruction (PI) model, a modified form of flipped classroom, requires that students gain first exposure prior to class, and uses quizzes to help ensure that students come to class prepared (Mazur, 1997). Preclass online quizzes enables the instructor to practice Just-In-Time Teaching (Novak et al., 1999), which means that the instructor can tailor class activities to focus on the concepts that students find more challenging. Miller et al. (2014) measured the amount of time students took to respond to in-class, conceptual questions in two introductory physics courses taught using PI. During PI, students first respond individually to a quiz and then respond a second time to the same quiz after discussing their responses with peers for 2–5 minutes (Mazur, 1997; Crouch et al., 2001). Actual class time is structured around alternating mini-lectures and conceptual questions. This method resulted in significant learning gains when compared to traditional instruction, ranging from 0.49–0.74 over eight years of assessment at Harvard University (Crouch & Mazur, 2001). Research on the time taken by students to respond to questions has yielded invaluable insights on how students think and change conceptions.

The “Introduction to Biology” course at the Singapore University of Technology and Design (SUTD) is a general biology course designed for nonbiology majors, as students will eventually graduate with a degree in engineering or architecture. Hence, students enroll in this class with varying degrees of motivation. Many of them have had limited prior experiences and are convinced that they cannot cope with the expectation of biology because of the perceived perception that biology requires memorization of a large amount of information and difficult words (Ekici, 2010; Osborne & Collins, 2001; Zeidan, 2010; Çimer, 2012). The module is compulsory for all first-year students; hence, many students enter the course as a means to fulfill their degree requirements. This fuels our motivation to assess the impact of the flipped classroom instructional model on our students’ learning and class performance in a biology course.

Based on literature, we hypothesized that the integration of the instructional videos with conceptual questions and hands-on, in-class activities would result in improved students’ test scores and perceptions of the introductory biology module.

The flipped classroom was implemented on two batches of SUTD students during five weeks of term 3 in the spring of 2016 and 2017, respectively. We prepared five sets of lessons that contained both flipped classroom and hands-on, in-class activities for the learning of advanced topics in biology, namely cell cycle, fly genetics, human genetics, cell signaling, and cancer.

We designed a flipped classroom model, inspired by Eric Mazur’s method of PI, where each week is broken up into lecture 1 (preclass video recordings), cohort 1 (in-class activities), lecture 2 (traditional lecture), and cohort 2 (in-class activities) (Figure 1). At the beginning of the first cohort, students were given a short quiz, followed by 5 minutes of peer discussion and the same quiz again. The in-class active learning activities were designed to reinforce and delve deeper into concepts covered in the lectures. With this plan, we embarked on a pedagogical experiment in the implementation of the flipped classroom in our course. The first lecture of each week was flipped, while keeping the second lecture was traditional. The second lecture was carried out in an auditorium with 250 students. Another two lessons each week were held in smaller classrooms (i.e., cohort classes), where hands-on activities were carried out for 50 students with two instructors per class. In contrast, in 2015, prior to the change, the method of the first lecture was also traditional. We decided to keep the mid-week lecture traditional so that the course lead would have an opportunity to ensure that all students were coping well in their respective cohorts, to reinforce the general objectives for the week, and also make important announcements. We were also concerned that our students would not be able to cope if both lectures were flipped, instead of one. The same team of eight faculty members taught the course throughout both 2016 and 2017.

Each flipped lesson consisted of only video recordings in 2016. However, students provided feedback that it was challenging for them to follow. Hence, in 2017, we provided students with video recordings, PowerPoint slides, and a list of keywords. This was designed to facilitate the auditory, visual, and reading/writing learners. Students were required to immediately attempt an online preclass quiz. Students were also assessed using a 10-minute quiz consisting of five multiple-choice questions at the beginning of the first cohort class lesson each week to further gauge their understanding of the topic. We found that having a short quiz at the beginning of class helped to boost attendance and punctuality for class, especially the classes that started at 8:30 a.m. In 2016, we used a single quiz and each quiz contributed to 3% of the final grades. It was observed that students were visibly stressed with this format. Hence, in 2017, we decided to adopt Eric Mazur’s PI model. The in-class quizzes were delivered twice, the first attempt (10 minutes) individually followed by a five-minute, peer-group discussion of the questions. The second individual attempt (5 minutes) was after the group discussion. The questions for the second attempt were similar to the first, except that they were randomized. Students chose their own peers for discussion, with three to five students per group. This approach was well-received by our students and it significantly helped to encourage discussion of key concepts and shared learning among peers. Scores for all three quizzes contributed to students’ overall grades, which was a source of extrinsic motivation for them. All quizzes were delivered using our university’s learning management system, Blackboard.

Once in class, students used the content they had learned in the flipped classroom to complete various in-class activities that target SUTD’s kinesthetic learners. These activities included real and virtual laboratory exercises, as well as case studies relevant to the introductory topics in biology.

An Institutional Review Board (IRB) approval was applied for and granted by the SUTD-IRB committee. The IRB reference number is 16-124.

Student evaluations of flipped classroom were collected at the end of the course for 2017, which included nine multiple-choice and two open-ended questions. The open-ended questions asked in the survey were (1) Do you have any general comments about the flipped classroom (e.g., advantages and/or disadvantages of the flipped classroom for learning biology)? (2) List your suggestions of how to improve the flipped lessons for learning biology. Students’ responses to the open-ended questions were categorized into positive, negative, and ambivalent by two individuals (one student researcher and one faculty) and the categorization was triple-checked by another faculty.

The results of the in-class quizzes were analyzed for the year 2017 for six out of the nine cohorts. The reason for not including the other three cohorts was because these students have their cohort lessons on Mondays and answer a different set of quiz questions compared to the six cohorts on Tuesdays. The quiz scores before and after the peer discussion in groups were compared. Quiz scores from weeks 9 (second week) and 13 (final week) were compared as a measure of consistency over the weeks. We chose week 9 rather than week 8 to compare, as being the first week of the course may have an added variable of adaptation of students to the method of learning and evaluation. It must be noted that week 9 covers fly genetics and is mathematical, while week 13 is focused on cancer that has no math and is possibly more relevant to students. This may have an implication on the results obtained. Similar comparison was also performed on students’ response times to the quizzes before and after the peer-group discussion and a t-test was conducted to study the significance of the difference. Response times to the quizzes were automatically captured by the learning management system (via Blackboard) as the total time taken by the student from the moment he/she clicks start until clicking submit.

To examine if the flipped classroom has helped students’ achieve better learning, we compared the final examination scores before we conducted the flipped classroom in 2015 and after in 2016 and 2017, respectively. Even though a pretest was not done for these students, students from cohorts 2015, 2016, and 2017 were considered comparable as the university admission criteria, which includes strict entry score requirements and rigorous interview sessions, have remained consistent. A normalization of scores was done by dividing the exam scores from 2016 and 2017 by the average score for 2015 and multiplying by 100%. The exam format (20 multiple-choice questions and five structured questions) and concepts that were tested were similar over the three years.

All students were first-year undergraduates at SUTD, Singapore. All students had similar course loads and schedules. Student surveys in 2015, 2016, and 2017 have consistently revealed that about half of the students enrolled were nonmajors in biology (proficiency up to Secondary Two level).

The summary of student opinion surveys based on their perceptions of the flipped classroom instructional model is presented in Table 1, which contains the survey questions with the respective responses received. A total of 331 students responded to the survey. We organized students’ responses to the statements based on flexibility (time management, questions 3–5), preparation (support for class, questions 6–8), and perception (overall sentiments, questions 1, 2, and 9) for ease of interpretation. The data obtained are illustrated in Figure 2. It is apparent that a majority of students found the flipped classroom engaging. Most students agreed that it helped them with preparation for class and scheduling of self-directed learning.

Figure 3 shows students’ responses to the open-ended questions. A total of 182 students responded to the survey. The responses are organized into positive (n = 73), negative (n = 70), ambivalent (n = 29), and no response (n = 10). “No response” refers to students who stated “no comments” in the survey. “Ambivalent” refers to responses that contain both positive and negative comments. We found that we could sort the positive and negative student opinions into six categories, namely, content quality, scheduling, preparation for class, self-directed learning, quiz, and comparison to traditional lecture. Three examples of students’ opinions for each category of response are selected and presented in Tables 2 and 3.

In general, the negative comments were lengthier than that of the positive responses. It is interesting to note that an equal number of students felt strongly positive and strongly negative for each category respectively. Here are three examples of ambivalent responses received:

“I like having the information available to us to learn at our own pace but I resent being made to watch long videos during my free time on the weekend.”

“I felt that it was very useful to be able to rewind the lecture as and when I needed so as to properly catch all the information being shared by the lecturer. However, I felt that despite watching the videos and doing the online quizzes, I still had some difficulties doing the quiz during the first cohort.”

“In general, I feel flipped classroom is a good avenue to prepare students for the upcoming classes. However, I feel that the content of the flipped classroom and the tutorials feel rather distant making it feel rather pointless at times for the flipped classroom.”

Student performance on the introduction to biology module delivered using the flipped classroom model was assessed by a pre- and posttest design. Quiz scores before and after peer-peer group discussion from six cohorts (n = 269 students) at week 9 were combined and plotted as number of students against percentage scores in Figure 4a. Before discussion, the highest group (score) was at 80%, obtained by 80 students, corresponding to 29.7% of the student population. There were 126 students (46.8%) who achieved a score of 60% and below. There were 54 students (20.1%) who had a full score of 100% before discussion. Notably, after the group discussion, the highest group was at 100%, which was achieved by 220 students, corresponding to 81.8% of the student population. This was a noteworthy increase of 166 students as compared to before the discussion. Only 11 students, (4.09%) scored 60% and below after the discussion.

We also looked at quiz scores before and after the discussion from six cohorts (n = 233 students) at the final week 13 (Figure 4b). This was designed to evaluate if the trends observed in the student scores before and after the peer discussion at week 9 would be replicated at week 13. In general, there was a proportional increase in the number of students with quiz scores, similar to that of week 9. Before the group discussion, the highest group (score) was already at a full score of 100%, obtained by 87 students, corresponding to 37.4% of the student population. There were 63 students (27%) who achieved a score of 60% and below. After discussion, the highest group remained at 100%, achieved by 221 students, and corresponding to 94.8% of the student population. This was a significant increase of 134 students as compared to that before the discussion. Remarkably, only two students scored 60% and below after discussion at week 13.

Figures 5a and 5b show the average time taken for correct answers on the conceptual quizzes both before and after the peer discussion at weeks 9 and 13, respectively. Students were given 10 minutes to complete the quiz (before) and 5 minutes for the quiz after the peer discussion. At week 9, before peer discussion, the average response time was 8.08 minutes. The response time dropped to 1.42 minutes after the peer discussion. This was a significant decrease of 82.5% (p < 0.001). A similar general trend in the average response times was noticed at week 13. Before the peer discussion, the average response time was 5.1 minutes. The response time dropped to 1.02 minutes after the peer discussion. This corresponds to a significant decrease of 80.1% (p < 0.001). In addition, students took significantly less time to respond with the correct answer for both before and after discussion quizzes at week 13 as compared to week 9 (p < 0.001).

To examine if the flipped classroom approach has enhanced students’ learning, students’ performance in the final exams was compared before and after implementing the flipped learning pedagogy (Figure 6). In 2015, the year before we started flipped classroom, 307 students enrolled in this undergraduate biology course at SUTD. We used the average score obtained in 2015 to normalize the average scores for the following two years. We then categorized the students into three bands, high (> 80%), middle (< 79.9% and > 60%) and low (< 59.9%). The breakdown of student percentages in each score band for 2015 indicated that 21.5%, 56.6%, and 21.8% of the students were in the high, middle, and low bands, respectively. In 2016, the first time that the flipped classroom was delivered, 346 students were enrolled in the course and the normalized average score achieved in the final exam was 99.6%. This is not significant differently when compared to the results of 2015. The breakdown in different score bands indicates that the percentage distribution of students within each band also were similar.

In 2017, we implemented the flipped classroom for the second time. A total of 451 students sat for the final exams and achieved a normalized average score of 106%, which is a significant improvement from the results of 2015 and 2016 (p < 0.01). There was a notable difference in the percentage of students in the various score bands when compared to 2015 and 2016. The percentage of students within the high score band increased to 37.5%, whereas those in middle and low bands decreased to 43.7 and 18.8%, respectively.

One of the driving factors for integrating flipped classroom into our cohort-based, active learning pedagogy was to improve students’ learning and class performance in a biology course intended for nonmajor students at the undergraduate level. About half of first-year students each year at SUTD are nonmajors in biology (with proficiency of up to secondary 2 level) who plan to pursue careers in engineering or architecture. The biology course is compulsory for all first-year students and there is a high percentage of students who enroll into SUTD with a perceived notion that they do not require knowledge in biology and that biology consists mainly of memorization of information. We were looking for a strategy that incorporated student-centered and active learning into the biology curriculum.

The flipped classroom lesson can include readings or videos that must be carefully tailored and designed for students in order to prepare them for the in-class activities (Simon, 2020). The majority of teachers who responded to a recent poll preferred online videos over reading assignments to accomplish the goal of preparing students out of class for in-class active learning. Their students preferred videos also (Herreid & Schiller, 2013). Voice-over PowerPoint was reported to be straightforward and effective and can be produced without editing (Bretzmann, 2013). These findings motivated us to try a similar approach. We provided students with customized video recordings produced by the various instructors, along with the PowerPoint slides and a list of keywords. In addition, we ensured that the duration of each video recording did not exceed 20 minutes as previous studies have shown that the optimal duration for students to focus is intervals of 20 minutes (Enfield, 2013; Mason et al., 2013). Tremendous time and effort was put in by instructors to create the flipped classroom material and to ensure that they were well-aligned with the subsequent in-class exercises of our cohort-based learning.

As this was our first time to implement the integrated pedagogy, we were concerned that our students would be initially resistant to the flipped classroom method that is new to them especially because it requires that they do homework rather than be first exposed to the subject content in class. An undesired outcome would be students coming unprepared to class and struggling to participate in the active learning phase of the course. This would pose an added challenge for instructors, who would have to repeat the flipped lesson to a certain degree in the classroom and may not be able to complete the in-class activities. We attempted to solve this diagnosed problem by delivering a short quiz in class, at the start of the lesson. In team learning, developed by Larry Michaelsen, students were given reading assignments prior to class and then in class they encountered individual quizzes, group quizzes, and finally case studies (Michaelsen, 1992; Michaelsen et al., 2002) and positive outcomes were reported. Herreid has described the successful use of Michaelsen’s method in science, technology, engineering and math (STEM) courses for this purpose (Herreid, 2002). In addition, Eric Mazur introduced the PI for teaching physics method, where students were asked to respond to conceptual questions before and after discussing their answers with their peers for two to five minutes (Mazur, 1997; Crouch et al., 2001). The quiz typically consisted of short questions that focused on a single topic. During PI, students first responded individually to the quiz, and then responded a second time to the same quiz after discussing their responses with a peer.

In a more recent study, graduate students enrolled in either a mammalian physiology course or a cardiovascular, renal, and respiratory function in health and disease course felt that the routine quizzes given at the beginning of each session motivated much greater preclass preparation than they were accustomed to and that the quizzes facilitated classroom discussion on important concepts (Tune et al., 2013). We adopted a slightly modified version of the approaches previously described and assigned 3% (before discussion: 1.5%, after discussion: 1.5%) of the students’ grade to each quiz per week. Our students were informed of this at the beginning of the course and the majority of them made it a point to be punctual for class so as to not miss the quiz. Notably, our instructors shared that during the five minute peer-discussion period, their students were completely engaged in dialogue with their classmates regarding the answers for the quiz. The effectiveness of the peer discussion was reinforced by our data showing that only 55 students achieved a full score before the discussion, as compared to 220 students after the discussion at week 9. In addition, our students required only 1.42 minutes to respond to the conceptual questions after discussion, as compared to 8.08 minutes needed before discussion at week 9. These trends were observed consistently at week 13. Interestingly, Mazur (1997) reported that the average response time drops from 20%–30% to 10% shorter for correct than for incorrect answers before and after peer instruction, respectively. This could be another meaningful parameter for us to evaluate in the future.

A major objective for integrating flipped classroom into our biology course was to encourage student engagement and to enhance their perception of biology. Based on students’ written feedback from our study, we were pleased to find out that a majority of students felt strongly that the flipped classroom helped in their preparation for class and provided flexibility of time for studying. In particular, students agreed that the flipped classroom method provided them with the necessary background knowledge to be prepared for the cohort exercises. It allowed them to systematize their weekend studying, and lessened the strain during the week day. They recognized that it freed up the cohort time for active learning. Most of the students genuinely liked the flipped classroom and would recommend it to a friend. This was consistent with other publications including Ingram et al. (2014), who implemented the flipped learning method in fourth- and fifth-grade mathematics classes. The results of their study demonstrated that students gained increased interest in the subject area. The majority of participants also expressed desire to have their classes “flipped” in the next school year (62% in fourth grade and 59% in fifth grade, respectively).

We were intrigued to discover that 182 students voluntarily responded to the open-ended question in the survey and that there was about an equal number of strongly positive and negative comments received. We found a similar study that reported that students’ opinions varied greatly with approximately half of the students reporting increased enthusiasm after the flipped classroom experience, and the other half indicating continued or worsened dissatisfaction (Tune et al., 2013). We feel that the disparity in opinions in our study could be attributed to the demographic profile of our students enrolled in the course at SUTD. Student surveys in 2015, 2016, and 2017 had consistently revealed that about half of the students were nonmajors in biology. It is a possibility that students with prior knowledge of biology found the flipped classroom easy to follow in terms of duration, content, and effectiveness for their self-paced learning as indicated by the positive opinions received. Meanwhile, the other half of the students with limited prior background in biology clearly struggled and found the material insufficient, and as a result had to spend more of their weekend time to complete the flipped lesson. An alternative explanation could be that students with prior knowledge of biology, taught traditionally throughout their education in Singapore, learned particular study skills such as memorization that suddenly does not work so well in this more open, concept-oriented, blended course. These students may have perceived that they did not learn as much, thus they resented that their time was being wasted for no good reason. Several of the negative comments in Table 3 support this alternative explanation. However, we are unable to confirm the possible explanations previously mentioned, as the survey was conducted in an anonymous manner. It poses an interesting challenge for us to find a way to modify our flipped classroom so that it is equally effective for the two distinct groups of students with differing backgrounds in biology.

The evidence from the current literature for statistically significant increases in exam scores using flipped classrooms is weak (Bormann, 2014). Hence, we were curious to examine if the flipped classroom had any effect on our students’ learning. Students’ performance in the final exams before (in 2015) and after (2016 and 2017) implementing the flipped learning were compared. The results from our study suggested that the flipped lesson had a significant effect on students’ normalized average scores in the final exams when comparing 2015 to 2017. When we assessed students’ performances in the different score bands, we discovered that the flipped classroom method had helped to improve the scores of middle and low band students and there was a higher percentage of students within the high band category in 2017. One possible explanation for our observations is that the flipped classroom better engaged students. They took ownership of their studies and found the motivation to explore the course further. As for students who did not benefit from the flipped classroom pedagogy, they may have lacked the discipline and self-motivation that is needed to assimilate the lesson material on their own. The lack of improvement in student performance in the exams between 2015 and 2016 could be because it was the first time that the flipped classroom was implemented with new lesson material. Both instructors and students needed adjustment to this approach. Instructors identified the best way of executing the flipped lessons and improved lesson materials and quiz delivery method in 2017 based on feedback received in 2016.

The flipped classroom, with its use of video recordings that engage and motivate student learning, offered us a new model for teaching undergraduate biology to nonmajors at SUTD. It combines active, peer-peer, student-directed learning with content mastery that can be applied to solving real-world problems. We assessed students’ performance using a unique set of rubrics that included individual quizzes and postpeer discussion quizzes. The results showed that peer-peer discussion was extremely effective and resulted in higher quiz scores and reduced response times. A majority of students found the flipped classroom engaging and helpful for class preparation and scheduling of learning. The thoughtful integration of the preclass lesson material with active learning, in-class activities was crucial for this approach to be meaningful. The flipped classroom pedagogy evaluated in our study took up significant amounts of instructors’ time to prepare and implement, however it symbolizes an important first step toward inculcating a lifelong learning habit in our students.