
SILO 1.4 (DRAFT) Year 1, Term 4: Light and sound Focus: Angles Scope and sequence: Reflection, Refraction
Learning intention: Students explore the sources and behaviour of light and sound energy and plan their own experiments to investigate phenomena.
NSW Syllabus	Australian Curriculum (version 9.0)
"A student describes the characteristics and effects of common forms of energy, such as light and heat." (ST2-8PW-ST) "A student describes common forms of energy and explores some characteristics of sound energy." (ST1-8PW-S)	"Students learn to identify sources of light, recognise that light travels in a straight path and describe how shadows are formed and light can be reflected and refracted." (AC9S5U03) "Students learn to explore different actions to make sounds and how to make a variety of sounds, and recognise that sound energy causes objects to vibrate." (AC9S2U02)

Introduction to light and sound

Play the hearing game, 'Heads down, thumbs up'.
Play the looking game, 'I spy'.

Light and sound both travel in waves. In this unit we will jump back and forth when investigating light and sound but the following section compares the speed of light and sound.

The speed of light and the speed of sound

The speed of light is the fastest thing that we know of in the universe. The speed of sound is also very fast but nowhere near as fast as light. We have probably all seen examples of this during a thunderstorm as we notice the lighting before we hear the thunder. The speed of sound is around 343 metres per second (m/s) but the speed of light is around 299,792,458 m/s. How can we make sense of such big numbers? Here is a comparison which might help:

Q: If you measure how far light travels in a single second, how long would it take sound to travel the same distance?

A: It would take around 10 days!

Musical examples of sound

The speed of sound waves is known as the frequency which is measured by the number of cycles which occur every second. The following animation (0:53) was made by a girl in Year 6. It is explain the science behind stringed instruments.

Does the amount of water in a bottle make the sound higher or lower?

The following video (2:14) investigates this question but to sure to let your students try this out for themselves before you show them the video.

A good explanation of this phenomena can be found at https://www.scienceworld.ca/resource/musical-bottles/.

Reflection

Light travels in straight lines which can create some interesting results when reflective surfaces are involved.

Building a periscope

In this video (4:25) you will see how a periscope can be made to see around corners.

Colour wheels

A colour wheel can be attached to a pencil and spun to create the visual effect of merging all of the colours into white.

https://www.pngegg.com/en/png-oykqp

Refraction

K.Venkataramana, CC BY-SA 4.0, via Wikimedia Commons

The Doppler effect

The Doppler effect describes how moving objects which emit waves affect the perceived frequency of those waves to observers. This phenomenon is named after the physicist Christian Doppler, who described it in 1842. The following video (3:02) explains this phenomenon in the common form of sound but also looks at light and stars as another example of the Doppler effect.

Sonic booms

This short video (0:45) explains the physics behind sonic booms.

Cracking a whip is another way to create a sonic boom. The following video (0:06) shows Brendan cracking a whip for the first time in his life before purchasing one from a vendor at the Tamworth Country Music Festival.

Risk assessment: Making and/or using whips is an engaging activity for children but care should be taken that the students are well clear of cracking whips to ensure their safety. Click on the following risk assessment icon for additional information.