2nd Grade · Ages 7–8
The Difference Year
Seven is when a child stops accepting the tool they were handed and starts asking what the tool is actually doing.
- 1 Hard Thing
- 5 days · 105 minutes
- 3 unmarkable questions
The Hard Thing · about a grade above
The Broken Ruler
Your ruler snapped. The only piece left runs from 4 cm to 15 cm — the zero is gone forever. Measure a pencil and tell me it is exactly 9 cm long.
Stuck for ten minutes? Good. Open one hint, not three.
1Hint 1
You are allowed to start the pencil anywhere on the ruler you like.
2Hint 2
Put the blunt end on the 4. Where does the point have to land?
3Hint 3
A length is how far apart two marks are. It has nothing to do with where zero used to be.
The answer — only after you have written something down
Line the pencil up with one end on the 4 and check the other end lands on the 13, because 13 − 4 = 9. Any two marks nine apart do the job: 5 and 14, or 6 and 15.
The genius move
“A measurement is a difference, not a place.”
Five days, five muscles
The week
Never the same muscle two days running. The weekend is not on this list on purpose — being bored is the sixth muscle and it needs two clear days.
- MondayThe Hard Thing
The Broken Ruler. Do not hand over a whole ruler as a rescue.
25 min - TuesdayBuild
Make your own broken ruler out of card, numbered from 37. Measure the kitchen table with it.
25 min - WednesdayRead up
A page of a manual, a recipe or an instruction sheet written for adults. Underline every number.
20 min - ThursdayTeach
Teach the broken ruler to somebody and time how long it takes them to see it.
15 min - FridayBreak
Measure the same thing five times. Do you get the same answer five times? Work out why not.
20 min
Start Monday now
Read the problem once more, out loud, and press start. Solving it is not the measurement.
Nothing rung today yet
The twenty-five minutes
Four phases. The middle one is most of it, and it is meant to feel slow.
- 1SitRead the problem again, out loud. Write nothing yet.
- 2AttackTry the wrong thing. It is faster than thinking about the right one.
- 3StuckWrite down the exact place you are stuck. “I don’t get it” is not a place.
- 4LogOne sentence: what you will try tomorrow. Then close the book.
No answer key
Three questions you cannot mark
Ask one at dinner. Do not resolve it. A question that survives the washing-up is doing its job.
- ?1
How long is the coastline of an island, really?
- ?2
Is a metre a real thing, or did somebody just decide?
- ?3
What is the shortest thing that can be measured?
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
Lengths as differences, on a ruler with no zero.
Next year
Negative numbers — the same idea with the zero moved somewhere else.
The year after
Measuring what a ruler cannot reach: a tree's height from its shadow.
What lives on the desk this year
- A ruler, and permission to snap a card one
- Squared paper
- String, for the things a ruler cannot follow
- A kitchen scale
- A notebook with the date at the top of every page
The rest of 2nd Grade
One hard thing a day is the sharp end. It sits on top of an ordinary year.
Last updated: September 2026