Natural Selection Meets Flipped Mastery |

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Natural Selection Meets Flipped Mastery

Hassan Wilson
Biology Teacher, Friends Seminary
New York City, NY

The benefit of mastery learning has been known since Benjamin Bloom's research1 in the 1980s, as he sought to find a teaching method as effective as individual tutorial in the group setting. At the time, mastery learning was impractical because it entailed students working at their own pace and the teacher administering multiple individualized assessments. With today's technology (online quizzes with randomized questions, free video hosting sites, and learning management systems, to name a few), mastery learning is now possible.

Mastery and flipped learning complementary

The unit on natural selection in my 8th grade Introductory Biology course has been revamped by mastery and flipped learning. Mastery and flipped learning complement each other. Offloading lectures to videos allows students to work at their own pace students because they can watch or rewatch a lecture when they are ready.

The natural selection unit starts with an exploration, the Chips Are Down lab, where students simulate natural selection and are challenged by using this experience to hypothesize how populations evolve. After an initial hypothesis, students take notes from a video outlining Darwin's theory of evolution by natural selection. Using the principles of natural selection learned in the video and experienced in the exploration, students complete a problem set to practice generating hypotheses about different populations’ adaptations.

Students are then assigned differentiated case studies based on level of difficulty. For example, advanced students may have to analyze contradictory and incomplete data to hypothesize why humans evolved different skin colors. Struggling students analyze straightforward data to hypothesize why clovers have stripes and produce cyanide in some environments and not in others. These case studies, and tons of others related to biology, can be found on the National Center for Case Study Teaching in Science Web site.

Unit assessment

After students apply their understanding of natural selection to different scenarios through the problem set and case studies, they are asked to revise their initial hypothesis from the exploration about how populations, in general, evolve. After a one-on-one or small group discussion with me, students receive permission to sit for the unit assessment. If students are denied permission or underperform on the unit assessment, they are required to make corrections and complete remediation activities aligned to the deficiencies or misconceptions uncovered during our talk or unit assessment. Students who wish to demonstrate learning or explore the topic at a deeper level can tackle optional projects.

Tailored to students' needs and abilities

Combining both flipped and mastery in the natural selection unit has allowed me to strategically provide targeted intervention and differentiate content and assessments. In the past, advanced and struggling students had to complete the same assignments on the same days. The advanced students, who understood the concepts the first time they heard them from me, had to wait until the course caught up to their pace. Struggling students had to move on to the next lesson, whether they understood it or not. With flipped and mastery learning, students who are struggling, advanced, or in between all experience an education tailored to their needs and abilities.


1Bloom, B. 1984. “The 2 Sigma Problem: The Search for Methods of Group Instruction as Effective as One-to-One Tutoring.” Educational Researcher 13, 6: 4–16.