Swimming
For the grown-up beside a child who loves swimming.
The child's own door is Swimming on Spark & Anvil.
At the event
Three numbers to notice
- The pace clock. A set "on the :40" leaves from three places round the dial; on the :45, four. The send-off draws a shape.
- The hundredths on the board. 1:05.32 is one minute, five seconds and thirty-two hundredths; the colon and the point are different kinds of number.
- The letter beside a time (a B, an A, an AA). It says which line in a table the time is under. It is not a percentile.
On the way home, ask: “How many places on the clock did your set leave from today?”
Ask because you are curious, and let any answer stand. Print this page for a half-page card.
A short course for you
- The Pool Deck Is a Maths Room4 lessons. Four short lessons on the numbers every swim family already handles: a clock that counts to sixty, times kept to the hundredth, yards against metres, and a sport where the smaller number wins.
- What a Time Standard Means4 lessons. Four short lessons on the letters next to a child’s time: a base plus fixed steps, the straight line hidden in the table, why a letter is not a percentile, and why a best time is the luckiest swim of several.
- The Points Curve3 lessons. Three short lessons on the World Aquatics points table: a cube of a ratio, the table read backwards, and why near the top one percent of time is worth about three percent of points.
- A Century of Fast3 lessons. Three short lessons on the Olympic 100 m freestyle since 1908: the winners on a chart, a straight line against a curve, and why every line says something silly about the year 2100.
A little history, and what nobody knows
The clock
Counting in sixties began with the Sumerians in the third millennium BC and passed to the Babylonians, which is why a minute still has sixty seconds. Sixty has twelve divisors, and those divisors are where a pace clock’s shapes come from.
Why they chose sixty is not settled: historians find its origins less simple than the usual stories tell.
Source: Sexagesimal (Wikipedia)
The hundredths
At the 1972 Olympics in Munich, Gunnar Larsson and Tim McKee both swam the 400 m individual medley in 4:31.98. Larsson won by two thousandths of a second, and after that no swimming race was to be decided by less than a hundredth.
Which of the two was really faster cannot be known from a gap that small; the source does not say why the line was drawn at a hundredth.
Source: Swimming at the 1972 Summer Olympics, men’s 400 m individual medley (Wikipedia)
The same idea at every age
- Ages 3–5Bead a Length and 3 more
- Ages 6–8Fives Round the Clock and 3 more
- Ages 9–14The Star and 9 more
- Ages 15–18The Points Curve and 3 more
Your child will meet this idea again at every age. The tools and courses here are the part for you.