Lesson Plan: The Iron in the Ink
Subjects: Physics (X-ray science, synchrotron radiation), Chemistry (iron oxidation, mineralisation), Mathematics (Archimedes, integral calculus), History (medieval manuscripts, palaeontology), Materials Science.
Recommended grade: 9–12 (high school) and undergraduate STEM electives.
Duration: Two 50-minute sessions, or one 90-minute block.
Learning Objectives
By the end of this lesson, students will be able to:
- Explain what a palimpsest is and why erased text is recoverable in principle.
- Describe how a synchrotron generates intense X-rays and what X-ray fluorescence measures.
- Identify the role of iron-bearing minerals (iron-gall ink, pyrite, goethite, hematite) as durable molecular records.
- Connect the technique that recovered the Archimedes Palimpsest in 2005 to the technique that imaged Scotty's blood vessels in 2026.
- Reason about why Archimedes' Method of Mechanical Theorems foreshadows the integral calculus.
- Practise scientific scepticism by examining the twenty-year debate over Mary Schweitzer's 2005 soft-tissue claim and what was needed to settle it.
Session 1: The Manuscript
Warm-up (5 minutes)
Show students a piece of paper with a pencilled sentence erased. Ask: "If I told you the original sentence was very important, how could you read it?" Solicit answers. Steer toward "find traces left behind."
Define palimpsest: parchment scraped or washed to be reused. Greek palímpsēstos, literally "scraped again."
Reading (10 minutes)
Distribute the first half of "The Iron in the Ink" (Jerusalem 1229 to the synchrotron at Stanford in 2005). Students read silently, marking any term they cannot define.
Discussion (15 minutes)
Whole-class:
- Why did Johannes Myronas erase Archimedes? (Cost of parchment, obsolescence of the math, abundance of older books.)
- What is Method of Mechanical Theorems and why does it matter? (Archimedes' record of how he discovered theorems by mechanical analogy with infinite slices, anticipating integral calculus by ~1900 years.)
- What did Heiberg achieve in 1906 and where did he stop? (Read about half by eye with a magnifying glass; could not see ink hidden under thick prayers, mould, or forged paintings.)
Hands-on activity: "Build your own ink fluorescence" thought experiment (15 minutes)
Working in pairs, students sketch the workflow:
- A light source (a synchrotron generates X-rays a billion times brighter than a hospital scanner).
- A target (the parchment with iron-gall ink residue).
- A physical effect (X-rays at the right energy excite iron atoms; the iron emits its own characteristic X-rays, called fluorescence).
- A detector that records the fluorescence one pixel at a time.
- A map that pieces those pixels together into a readable image of the iron pattern.
Each pair labels their diagram with two technical terms they had to look up.
Exit ticket (5 minutes)
One sentence: "Why was iron, specifically, the key to reading the Archimedes Palimpsest?"
Session 2: The Dinosaur
Warm-up (5 minutes)
Show a photograph of Scotty (the world's largest Tyrannosaurus rex, in the Royal Saskatchewan Museum). Tell the discovery story: high-school teacher Robert Gebhardt finds a tooth and a tail vertebra in the Frenchman River badlands on 16 August 1991. Excavation takes more than two decades.
Reading (10 minutes)
Distribute the second half of the story (Saskatoon, 2026). Students read silently.
Mineralogy mini-lab (15 minutes)
Pass around (or project) reference specimens or images of:
- Pyrite (FeS₂): cubic gold-coloured crystals, "fool's gold."
- Goethite (FeO(OH)): rusty-orange streak, the most common iron-rust mineral.
- Hematite (Fe₂O₃): deep red metallic streak.
Students draw the chain: a dinosaur's blood vessels → buried in oxygen-poor mud → sulfur-bearing iron precipitates as pyrite templated on the original vessel walls → over millions of years, pyrite weathers in the presence of trace oxygen and water to goethite/hematite.
Two layers around Scotty's healed fracture are interpreted as the angiogenic vessels that grew during the dinosaur's life as it healed.
Discussion: Scepticism done right (15 minutes)
Provide the timeline:
- 2005: Mary Schweitzer publishes "Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex" in Science, working from MOR 1125, while at NC State.
- 2005–2010: critics propose bacterial biofilm contamination; replication is contested.
- 2010s: independent groups recover protein fragments and other organic markers from additional specimens.
- 2026: Mitchell et al. publish a 3D synchrotron map of pyrite-templated vessels with the dual-layer architecture expected of healing biology.
Discussion prompts:
- What kind of evidence would change your mind? (Independent replication. Multiple specimens. New techniques that do not share the same possible flaw.)
- Why was the original 2005 claim so controversial? (It violated the assumption that organic structures cannot survive 65+ million years.)
- What's the difference between "bacterial slime that mimics a blood vessel" and "iron-templated mineralised cast of a real blood vessel"? (Composition, geometry, crystal structure, and 3D architecture.)
Calculus connection (5 minutes)
Return to Archimedes' Method. Demonstrate by sketch how:
- The volume of a sphere of radius r can be derived by stacking infinitely many infinitely thin disk-slices and summing their volumes.
- This is the same logical move as a Riemann sum or definite integral.
- Newton (working c. 1665–1670) and Leibniz (publishing 1684) get formal credit for the calculus, but Archimedes had the central trick almost two thousand years earlier; it was just hidden under a prayer book until 2005.
Closing question (5 minutes)
In pairs: "Iron does not forget. What other elements, materials, or natural systems are 'memory devices' for science?" (Possible answers: tree rings, ice cores, isotopic ratios in tooth enamel, pollen in lakebed sediments, magnetic stripes in oceanic crust.)
Assessment
Short answer (one paragraph each):
- Define a synchrotron in your own words. Why is its X-ray beam useful for reading both medieval ink and dinosaur blood vessels?
- Compare the role of iron-gall ink in the Archimedes Palimpsest with the role of pyrite in Scotty's rib. What do they have in common?
- Imagine that, in 2050, a third synchrotron technique reveals something thought to be lost in a different specimen. Predict one example and explain what trace would have to survive.
Longer:
Write a 300-word essay arguing whether the boundary between "biology" and "fossil" is sharp or porous, citing both the 2005 Schweitzer controversy and the 2026 Mitchell paper.
Source materials and further reading
Primary papers and announcements:
- Mitchell, J. L. et al. Scientific Reports (2026): "In situ analysis of vascular structures in fractured Tyrannosaurus rex rib." DOI: 10.1038/s41598-025-06981-z
- Schweitzer, M. H. et al. Science 307, 1952–1955 (2005): "Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex."
- Bergmann, U. and SSRL/SLAC team (2005): X-ray Fluorescence Imaging of the Archimedes Palimpsest. SLAC press release, 16 June 2005.
Background:
- Netz, R. and Noel, W. The Archimedes Codex (2007). Accessible book-length account of the palimpsest's recovery.
- Heiberg, J. L. (1906–1908). Original Greek transcription, Hermes 42.
- The Conversation (28 April 2026): "I'm a physicist who studies fossils and I recently discovered preserved blood vessels in the world's largest T. rex."
Visual:
- Royal Saskatchewan Museum, "Unearthing Scotty," royalsaskmuseum.ca/trex/unearthing-scotty
- The Walters Art Museum, "Lost and Found: The Secrets of Archimedes," thewalters.org
Optional extensions
- Maths: Reproduce Archimedes' derivation of the volume of a sphere by inscribed and circumscribed cones, then show its equivalence to the modern integral.
- Chemistry: Look up the redox half-reactions that convert pyrite (FeS₂) to goethite (FeO(OH)) in the presence of water and oxygen. Calculate the standard cell potential.
- History: Trace the path of the Archimedes Palimpsest from 250 BCE Syracuse to 2026 Baltimore. Identify three points where the manuscript almost ceased to exist.
- Ethics / philosophy of science: Debate. Resolved: A claim that violates accepted theory should be presumed wrong until replicated by an independent group using a different method.
This lesson plan is part of the Time Rhymes daily series, which connects current events to historical patterns. timerhymes.com.