Why Twelve Notes
Four short lessons on the arithmetic inside music: a bar that has to add up, tempo as a rate, why the octave has twelve steps, and why loudness is measured on a log scale.
For grown-ups, from what HarmonyForge teaches children at Spark & Anvil.
Tune the water glasses
You'll need: Four or five matching glasses, a jug of water, a spoon.
- Fill the glasses to different heights and tap each one gently with the spoon.
- Before tapping, guess: does more water make the note higher or lower?
- Add or pour off water until two glasses sound the same note, then try to make one sound an octave above another.
- Talk about what changed: the water, the length of air, or how the glass rings.
A little history, and what nobody knows
Two inventors
Zhu Zaiyu in Ming China published an exact calculation of twelve equal semitones in 1584, and Simon Stevin worked out the same idea in Europe around 1605.
Whether Stevin knew of Zhu’s work is not known.
Source: Equal temperament (Wikipedia)
The same idea, with the world taken away
Walk round a circle of twelve places, seven steps at a time. Do you visit every place before you are back where you started?
Ask it, then let everyone say the answer in their own words. A child's rung on Spark & Anvil ends the same way, with the world gone and the numbers left.
The same idea at every age
- Ages 3–5Echo the Beat
- Ages 6–8Fill the Bar and 1 more
- Ages 9–14A Scale From Fifths and 4 more
- Ages 15–18Loudness Is Logarithmic and 1 more
Your child will meet this idea again at every age. The tools and courses here are the part for you.