Last year, in my 9th grade foundational Integrated Social Sciences class, I built a Day 1 activity around the historical flat earth myth. It was paired with a parallel lesson in 9th grade math, where students worked through Eratosthenes’ method for calculating the earth’s circumference using shadow angles at different latitudes among other geographic applications. This year, my new co-teacher and department member took the lead on expanding it into a 4-day inquiry, building out more gallery walk sources and structuring the sequence toward NHD and unit skills like source analysis, argumentation, and contextualization. Running a lesson series for the first time meant some rough patches, like awkward transitions or challenging source translations, but it worked out well and I am looking forward to running it next year.
Inquiry Structure
On the very first day of class, I did the break-up DBQ to get students thinking about sources and how to analyze them. They wrapped up the lesson with a simple debrief where they wrote a claim and a paragraph or so supporting it. In a previous blog post, I wrote about my philosophy on Day 1 activities; this one provided the fun energy and spirit of analysis I wanted to foster while also yielding a writing and argumentation sample to see what skill level each student was at. From there, we started the full four day inquiry that would include both instruction and practice of the same skills, pulling everything together with a source-based argumentative essay at the very end.
Day One
Day one was focused on unpacking the driving question, “Did medieval scholars and church leaders believe the earth was flat?”, alongside instruction on how different social science disciplines each provide a valuable lens for answering it. Students got a preview of the disciplinary sets they’d see in the gallery walk: history, geography, political science, anthropology, and economics, each contributing a different kind of evidence to the same question.
We also introduced a critical source on day one: an excerpt from Washington Irving’s 1828 biography of Columbus, where he invents a scene of Columbus defending a round earth against flat-earth professors and church fathers at the University of Salamanca. Irving fabricated this confrontation, but it stuck, and it’s a major reason the “medieval flat earth” myth persists in textbooks and popular history today. We introduced it early as a hinge point: students can sense on their own that something is off about this source (why does it read more like a story than an account?), but they don’t yet have the background knowledge or skills to explain why. We centered it here to make an early case for why sources and investigation matter, then used it as a foil for the rest of the inquiry, where students are either proving or disproving Irving’s version against the weight of the evidence.
Day Two
Day two was a gallery walk, with sources organized in sets of three by disciplinary lens. At each station, students looked for evidence bearing on the driving question while also reflecting on what that discipline’s lens added or changed about how they understood the topic. Some sources were tougher for 9th graders than expected, so next year we’ll have modified versions ready for those stations. I admit that I go back and forth on the issue of whether primary sources should be modified. Being a teacher rather than a historian means I usually land on the side of modifying when the classroom demands it. Maybe at some point I will be as good at source modification as the Stanford Digital Inquiry Group.
Day Three
Day three was spent analyzing the evidence, and we ran nearly all of it through a Kahoot to keep energy levels up. Rather than a separate activity, the Kahoot was the vehicle for the analysis itself: questions pushed students to clarify what a document was actually claiming, how its disciplinary lens shaped or limited that evidence, and where HIPP could explain why two sources agreed or diverged. Students discussed questions like “What makes Ptolemy a strong authority source?” or “Which pairing uses different methods to reach the same round-Earth conclusion?” in pairs before selecting their answer. The stakes of the kahoot kept more reluctant students engaged with the dense material, and having a partner provided an easy scaffold. It worked well. Homework was outlining a potential argument.
Day Four
Day four was argument drafting. Straightforward though not exactly engaging or fun. Students who’d stayed engaged during source analysis and took the outlining seriously wrote stronger essays. We were looking for a tri-partite thesis statement, particularly a counterclaim, and strong reasoning and HIPP analysis to corroborate documents and build a complex argument. I got that from quite a few of them at least.
The DBQ served as a great diagnostic for the following unit, where all the skills would continue to spiral. It also set up National History Day almost seamlessly, since sourcing, corroboration, argumentation, and contextualization are the same muscles NHD projects demand. Getting them practiced in week one also meant students had a deeper understanding of the “why” behind them rather than treating them as disparate skills. At least, that is what I hope they got from it.
Interdisciplinary Connection
The math connection was more than just surface level. My colleague’s first unit introduced a lot of ancient history of mathematics related to Archimedes, Euclid, and Eratosthenes and built toward a similar question that our inquiry was asking, just from the opposite direction. Where we handed students conflicting historical accounts and asked them to weigh evidence, the math classroom had students reconstruct Eratosthenes’ actual method: using the reported shadow angles at Syene and Alexandria, the (roughly) north-south distance between the two cities, and a proportion between arc length and central angle, students calculated the circumference of the Earth themselves. This came after the social sciences inquiry.
The math packet even localizes the concept for students: alongside the classical Alexandria-Syene problem, it asks them to calculate the sun’s angle at high noon in Shanghai, and to work out why the Tropic of Cancer marker in Shantou casts no shadow at all on the summer solstice. Students weren’t just calculating answers, they were replicating, with 9th grade geometry, the same evidence-based reasoning that Eratosthenes used over two thousand years ago to establish something the flat earth myth explicitly denies was ever in question: that ancient scholars had already measured the Earth, and measured it well.
I am incredibly lucky to have colleagues in the math department that appreciate the historical context of the math they teach. Euclid, Archimedes, and Eratosthenes are introduced as people working from a shared institution (the Library of Alexandria) and building on each other’s work, which quietly undercuts the “isolated genius” framing that also props up the Columbus myth. Later in the unit, a poster project has students research and present the history of pi approximations across cultures, including the methods of Liu Hui and Zu Chongzhi, alongside the Greek geometric tradition. Even when I cannot directly support the history of math being taught, I appreciate what this collaboration illustrates to students.
Both classrooms were teaching the same lesson in different languages. History and math are usually taught as if they ask different kinds of questions, one interpretive and one certain. But the flat earth inquiry and the Eratosthenes activity both ask students to build a defensible claim from incomplete, indirect evidence, and to trust the process of measurement and corroboration over intuition or received wisdom. A ninth grader who has done both comes away with the same underlying lesson: don’t ask “what do I already believe,” ask “what does the evidence actually support, and how would I know if I were wrong.”
Resources
There are no doubt some typos and formatting inconsistencies in these resources. I have not yet updated things for next year, but still wanted to post what we actually used. I hope some of it, even if just through inspiration, can be helpful in your classroom.
Day 1 Slides – I like the opening video clips, but there are so many to use as a hook.
Unit 1 Student Booklet – This includes more than the inquiry. The rest of the unit, as you can see, is NHD centered.
Gallery Walk Sources – Some ended up being more useful than others. These need the most refining before next year.
DBQ Writing Guide – Formatted, but not written, with AI. I have found Clause better at formatting tasks than other models.
Inquiry Poster v.1 – I want to redesign this as it looks a little too robotic. I made it in InDesign, but my lack of artistic ability definitely sets an effective glass ceiling on the visual quality of what I make.