Cup Telephone Distance Test
Sound is much clearer with taut string.
Teaching & key ideas
What you do: Speak through the cup with string taut, then loose.
What students see: Sound is much clearer with taut string.
Why it works: Vibrations travel through the tight string between cups.
Question to ask: Why does a loose string work poorly?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Why does a loose string work poorly?