Can you mix two photos so a stranger can't read them, but your friend can?
Open for the projector Present it step by step
Classroom mode
A question for the whole room
One story to open. A room full of ideas to test.
Ready in three steps
- Open the story.Read and try the first pages together.
- Pause for a prediction.At the story’s question, read its choices aloud. Invite a vote and ask, “What makes you think that?”
- Run it. Watch. Wonder.Choose the class’s prediction, run the experiment, and compare what happened with your guesses.
Different guesses are welcome. The experiment gives everyone something to rethink.
Something to put on paper
A one-page prediction and observation sheet. No answers included.
After the experiment: discussion notes
Talk about what happened
- Predict it first: hand a spy just one share. What fraction of the picture can they recover, and why?
- Predict what happens when we stack the two sheets — will the picture get sharper or fuzzier than the original, and why does ink act like an OR?
- Predict what leaks if we reuse one random sheet for two secrets — what could a spy line up to start cracking it?
Where it shows up in real life
- Hidden-message decoder toys where one sheet alone is just dots until you overlay the key
- Two tracing-paper scribbles held up to a sunny window so a shape darkens in
- Splitting a password so no single person — and no single piece — can open the safe alone
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