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← The Keyboard Is a Number Line

The Keyboard Is a Number Line

Four short lessons for parents of young pianists: twos and threes of black keys, finger numbers that mirror, twelve keys to an octave, and eighty-eight keys in all.

Spark & Whetstone · sparkwhetstone.org/learn/the-keyboard-is-a-number-line · CC BY-NC-SA 4.0. Answers are at the end, so you can try each question first.

Lesson 1. Twos and threes

The black keys come in groups of two and three, all the way up the keyboard. Young children find notes by those groups long before they can read music.

C is the white key just to the left of every group of two. Find the twos and every C follows.

Question. Which white key sits just to the left of each group of three black keys?

  1. The A key
  2. The C key
  3. The F key

Say it back. In your own words: how can a child find every C without counting keys?

Lesson 2. Finger numbers mirror

Piano music numbers the fingers on both hands from the thumb: thumb 1, little finger 5. So when both hands play up the keyboard, the right hand counts 1 to 5 and the left hand counts 5 to 1.

The middle finger is 3 on both hands, which is why it is a useful anchor.

Question. The left hand plays C, D, E, F, G, one finger per key, starting with the little finger. Which finger plays E?

  1. Finger 4
  2. Finger 3
  3. Finger 2

Say it back. In your own words: why do the two hands count in opposite directions?

Lesson 3. Twelve keys to an octave

From one C to the next C there are seven white keys and five black: twelve different keys before the names repeat. Each next key, white or black, is a half step.

Every major scale uses the same pattern of steps — whole, whole, half, whole, whole, whole, half — and the steps add up to twelve half steps.

Question. A whole step is two half steps. Starting on D, what is the note a whole step up?

  1. The note D♯
  2. The note F
  3. The note E

Say it back. In your own words: why do the note names repeat every twelve keys?

Lesson 4. Eighty-eight keys

A full piano has 88 keys: seven full sets of twelve plus four extra. The lowest note is an A that vibrates 27.5 times a second; each octave up doubles it.

Smaller pianos and keyboards often have 61 or 76 keys, which still carry the same pattern of twos and threes.

Question. A 61-key keyboard is how many full octaves of twelve, with how many left over?

  1. Five octaves and one key
  2. Four octaves and thirteen keys
  3. Six octaves exactly

Say it back. In your own words: where does the number 88 come from?

At the table: A paper keyboard on the table

Players: One child and a grown-up, ages 4 and up. You'll need: A long strip of paper, a ruler, a black pencil or crayon.

  1. Draw fourteen white keys side by side on the strip.
  2. Colour black keys in groups of two and three over the gaps, the way a piano does.
  3. Take turns finding every group of two, then every C, then every F.
  4. Put a thumb on a C and play "five fingers" on the table: 1, 2, 3, 4, 5, then back.

Answers

  1. The F key — F is just left of each group of three black keys, as C is just left of each group of two.
  2. Finger 3 — C is 5, D is 4, E is 3. The middle finger plays the middle note on either hand.
  3. The note E — D to D♯ is a half step, D♯ to E is another: so a whole step up from D is E.
  4. Five octaves and one key — 61 = 5 × 12 + 1: five full octaves, usually from C to C with the top C as the extra key.