Swimming

The ladder

1. Ages 3–5
   • Ribbons for the DucklingsHand out ribbons in the order the ducklings finishOpen →
   • Kick FiveKick and count in fives with your bodyOpen →
   • Lift on the TopLift your finger as the clock hand reaches the topOpen →
   • Bead a LengthSlide a bead for each length, then compare stringsOpen →
2. Ages 6–8
   • Heats of EightFill heats of eight and place the leftover swimmersOpen →
   • Fives Round the ClockSkip-count by fives round the pace clockOpen →
   • Two PoolsWalk the same length in yards and metres and compare stepsOpen →
   • Send-offsPredict each leave time on a send-off clockOpen →
3. Ages 9–14
   • How Much Water Is in the Pool?Work out a pool's volume, then its gallonsOpen →
   • Catch-Up in the LaneTurn a head start into a gap and close itOpen →
   • A Century of FastPlot winning times, fit a line and read the missesOpen →
   and 7 more

   • The Pace ClockRead the pace clock and hold a paceOpen →
   • The Hidden BaseFind where a line of cut times meets step zeroOpen →
   • The HundredthsLine up times to the hundredth and catch the trapsOpen →
   • Trust the Percent Bot?Decide whether to trust a bot's percent, then check itOpen →
   • The StarPredict how many spots a send-off visits on the clockOpen →
   • The StopwatchTime something real with laps on a stopwatchOpen →
   • Cut & ConvertWork a cut backwards and convert yards to metresOpen →
4. Ages 15–18
   • The Points CurveCompute swim points from a cube and invert itOpen →
   • Speed Is a ProductTrade stroke rate against distance per strokeOpen →
   • A Best Time Is a MinimumSimulate a season and compare best and typical swimsOpen →
   • Who Is in the Denominator?Sort three percentage sentences by who they compare againstOpen →

The pool deck also has five strands of its own: the clock, the touchpad, the lane rope, the standards and the model.

Two rules every rung keeps

The Fade Rule. Every game ends on a plain screen: the same numbers with the swimming words gone, so the maths leaves with you.

The Own-Lane Rule. Your numbers are compared only with your own past, never with anyone else's, and they stay on this device.

Problems built on something you love help most when the context carries the maths, not when it decorates it. These ladders are a design, not a promise.

Ask a grown-up tonight: “How many places on the clock did your set leave from today?”