Dave Burzillo
Big History Teacher, Massachusetts, USA

About the author: Dave has taught for over 30 years, more than 25 of them at his current school, a private high school in Weston, MA. For the last 7 years, he has taught BHP to ninth, eleventh, and twelfth graders in classes that range in size from 12 to 16 students. His school runs on a trimester system, which gives him about 90 days to cover 13.8 billion years of history. Recently, Dave began offering an online Big History Project course in the summer.

The eight thresholds of increasing complexity

In Big History, the very first lesson of the very first unit concludes with the introduction of the eight thresholds. That’s because really there is no moving forward without a basic understanding of each threshold and a perspective on where they occur on the 14-billion-year spectrum. To gloss over them would be like taking music lessons without learning each note in the scale.

What are the eight thresholds? In his TED Talk, after David Christian establishes BHP’s driving question—“How did everything come to be the way it is today?”—he identifies the thresholds as key moments in our Universe after which there was no turning back. Nothing would ever be as it was before. The Big Bang, the lighting up of the first stars, the appearance of life on Earth, the Modern Revolution—these are just a few of those moments. Together, the eight thresholds make up the core narrative of the course.

By the end of the year, I want my students to deeply understand the thresholds and to be able to describe the conditions that brought each about as well as the resulting new complexities. However, at the beginning, my goal is simply for students to learn what the thresholds are so they can grasp the overall narrative. Although they’ll learn more details about the thresholds later, this early overview is essential in enabling students to connect ideas across units.

In Unit 2, the article “Complexity and Thresholds” also offers an excellent introduction, and students explore the notion even more in classroom activities.

To reinforce what they’ve learned in the Threshold 1 video, reading, and activity, I break my students into small groups and give them a pop quiz in which they need to list the eight thresholds. I’ll often have them do this first in class, on a couple of consecutive days, before asking them to do it on their own. I also like to take a few minutes in class and go around the room, having students name a different threshold (in the correct order, of course!). I ask students to volunteer to name all eight thresholds of the course, and pretty quickly they’re all able to do this. Each of these exercises takes only a few minutes of class time, and although these are low-stakes assessments, I think there’s great value in students learning the thresholds from the start. This knowledge will help them understand how the course is organized; give them insight into how the disciplines and content for each unit were chosen; and help them keep in mind where we’ve come from and where we’re going in the course.

Just like that musician who had to learn the notes of the scale in order play chords and melodies later, my students are able to approach BHP’s increasingly complex ideas with a fundamental knowledge that makes even the most difficult lessons engaging.


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