Light and Sound

This lesson explores the nature of light and sound.
It was run outdoors.

Make shadows using the sun - hand shadows or by holding cloth in the path of the sun.
Discussion:
Shadows are where the light is blocked. The cloth is 'opaque'.
Light goes in straight lines. Follow the line from the sun to the cloth to the shadow where the cloth blocks the line of the sun.

Look through scratched plastic to separate light colours.
Discussion:
Light is made up of a mixture of colours (each with their own ‘wavelength’).
Sunlight (called 'white light') is all the colours mixed together (opposite of paint: when all the paint colours are mixed we get brown or black paint).

Look through red and blue filters.
Discussion:
These filters take away some of the colours, to make a new mixture, so we see a new colour.

Sound is made up of a mixture too, but of frequencies: high [sing] frequencies and low [sing].
Even one note is a mixture of frequencies (called the harmonics).

Make a laughing cup.
Add some little rocks to see [vibration].
The vibration of the cup vibrates the air molecules which vibrates our ear drum.

Both light and sound are waves that travel.
See how the waves travel with this model (slinky on the ground).
Light like this (transverse). Sound like this (longitudinal)

Discuss pitch. Demonstrate different sized cups making different sounds.
Shorter cup is higher sound (faster vibrations) taller cup is lower sound (slower vibrations).

Light: longer wavelengths are towards the red end of the rainbow, shorter towards blue (and UV).

Ukulele: show the string - predict wether the longer string makes a lower or higher note.
Sing a song together, using laughing cups.