The Shadow Stick
The idea: a shadow's angle can measure something too big to walk round.
Read it
Who is in this book
-
Beto a child of the Green Takes things apart -
Ledger No object leaves without a slip that says what you saw, before what you think from BackstageQuest -
Lan a child of the Green Goes first; makes a friend in a minute -
Bevel An angle is how much of a turn, measured in degrees round a circle from MeasureQuest -
Rod Length is how far from one end to the other, in steps of one unit from MeasureQuest
Every recurring character has a short tune, so you can tell who is on stage before a word is said. The tunes play only when you tap, and the Reading Access sound switch turns them off.
The Honest Page
Which parts are true, stretched or made up — and what does nobody know?
True
- Eratosthenes, a scholar in Alexandria about 240 BCE, worked out the size of the Earth from the angle of a noon shadow and the distance to Syene. Source
- 7.2 degrees is a fiftieth of a full turn, and fifty times 5000 stadia is 250,000 stadia.
- A shadow stick on a plate is called a gnomon, the oldest part of a sundial. Source
Stretched
- Sticks in Syene had no shadow at all at noon on midsummer's day. What we simplified: Syene was very close to, not exactly on, the line where the midsummer sun is straight overhead, so its noon shadow was tiny.
Made up
- The Lending Museum and its bronze plate are made up. Ledger comes from BackstageQuest, and Bevel and Rod from MeasureQuest.
Nobody knows
- We don't know exactly how long Eratosthenes' stadion was, so we can't say how close his answer came to the real size of the Earth. Source
Tell it back
Tell the story in your own words: who was there, what went wrong, and what they found out. Then the second loan slip, stamped, in the children's folder goes on your belt.
On your belt: the second loan slip, stamped, in the children's folder.
Your belt lives on this device. Nothing is sent anywhere.
Ring the hammer for someone
Pick this book for someone younger. The link carries only the book, and it will wait for them on the Green.