8th Grade · Ages 13–14
The Counting-Information Year
Thirteen is old enough for the most useful habit an adult has: proving a thing is possible before spending a week looking for how.
- 1 Hard Thing
- 5 days · 120 minutes
- 3 unmarkable questions
Ready?
8th Grade · Twelve Coins
Thirteen is old enough for the most useful habit an adult has: proving a thing is possible before spending a week looking for how.
Full screen — no distractions
Where this goes
The ladder
The same idea, three times, roughly a year apart. This is what depth looks like from the outside.
This year
Twelve coins, three weighings, direction unknown.
Next year
The general rule: n weighings handle (3ⁿ − 3)/2 coins. Derive it rather than look it up.
The year after
Information theory — and the discovery that this puzzle and file compression are the same puzzle.
What lives on the desk this year
- A sheet large enough for the whole tree
- Coins and a balance
- A ruler, for drawing branches straight
- A folder of proofs you wrote yourself
- A question you have been carrying for months
The rest of 8th Grade
One hard thing a day is the sharp end. It sits on top of an ordinary year.
Last updated: September 2026