for teachers · no sign-up, no setup

Six things you can prove in two minutes.

Each one is a single idea on a full screen, with one control and instant sound — built for a projector or a shared tablet, in the middle of a lesson you were already teaching. Nothing to install and nothing to read first. Every one ends with the sentence to put on the board.

Grades 4–6about 1 min

Halve the string. What happens to the note?

Fractions · halves, thirds, quarters

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Grades 5–8about 1.5 min

Two hands, two clocks. When do they meet?

Lowest common multiple · highest common factor

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Grades 6–8about 1.5 min

Why you cannot add exponents

Indices & powers · why 2^a + 2^b ≠ 2^(a+b)

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Grades 5–8about 1 min

How long is a sound?

Measurement · wavelength = speed ÷ frequency · scale drawing

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Grades 6–8about 1.5 min

Pitch times length is always the same number

Inverse proportion · the reciprocal graph y = k ÷ x

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Grades 5–8about 1 min

Two notes almost the same — hear the difference

Subtraction · rates · what a 'beat' counts

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Then go deeper

Every demonstration links to the full room it came from, where the same idea is taken apart properly — with the algebra, the classroom exercises and the instrument itself to play. Start at the syllabus map if you would rather browse by topic, or the maths playground for the grade 4–8 activities.