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LIGHT - Travel & Reflection


Students gather evidence to support their predictions about how light travels and is reflected

Students learn:

SCIENCE Identify scientific principles underlying bhaviour of light
TECHNOLOGY Record and analyse data
ART Blended multimedia elements
ENGINEERING Design, build and test experimental device(s)
MATHEMATICS Use comparative data to differentiate materials



Like a rubber ball, light bounces off most things it hits - Light is made up of lots of things that bounce.

  1. When light falls on something, mostly, it is like a hand-full of rubber balls being thrown - not just one ball.
  2. When light travels to something opaque, some of this light stops there - BUT, some of this light bounces off.
  3. When light travels to something translucent or transparent, most of the light passes through - BUT, some of this light bounces off.
  4. When light bounces off things and travels to your eyes, this information is passed to your brain and you are able to see. 1)

When light bounces off of things, scientists call this reflection

To explain how light travels and bounces off of things, scientists use 'ray diagrams'.

A ray diagram is a drawing with arrows that shows where the light is coming from, what it is hitting, and where it travels after it bounces off of something - detailed science resources from lightandmatter - Read more...

Light Travels from the sun & objects

Fig 1. Two Ray Diagrams: How Light Travels From The Sun & From Objects

If you need more help, check out the on-line How We See Things interactive (lower down this page) about reflection and refraction




Example materials list - One of each item is required for each student group (say each 4-5 students):

  • A cheap LED torch (or similar $2 - $5 light source) for each group
  • A light-activated 'night-light' or similar device that turns on/off in the presence/absence of light (available for around $8 - $10 each - One can be shared by multiple groups if necessary).
  • A light 'baffle' - A square, opaque dividing strip that is 300mm hight x 300mm long and less that 150mm deep (for example, a 300mm square cut from the side of a thick/corrugated cardboard card-board box or similar)
  • Any small (150mm x 150mm or larger) mirror (see below - used only for testing purposes).
  • Scissors and glue/tape available for each group for cutting/gluing the A4 paper sheet. The A4 sheet should be standard white photo-copy/printer paper, but any other, additional colours can be used.
  • Ideally, students should work in a shaded area where their night-light is turned away from any windows/doors or other sources of bright/reflected light.
  • A computer or similar device connected to Internet for access to on-line interactives
  • Google sheet or science journal to record results

Make a guess (your 'hypothesis') how you will design and build an optical device to make the light from the torch loop around and turn the night-light on/off.


SAFETY WARNING: Students MUST NOT look directly into the torch/light at ANY time.

Before commencing the task, the student and teacher must discuss and agree about SAFE ways how to test whether the light is travelling in a loop!

When the teacher is confident that students understand and will comply with the safety rules:

  • Each group must place their night-light and a torch parallel to each-other so that no light from the torch can fall on the night-light.
  • In addition, the square cardboard (or similar) 'baffle' should be placed vertically between the night-light and torch to ensure there is no 'short circuit' for light to travel between the torch and the night-light.
  • Students must design a device using only one sheet of A4 paper to reflect or reflect sufficient light to turn the night-light on/off.
  • The teacher should use a mirror placed at the end of the baffle to reflect light back and prove that the sytem will work using light reflected back to the night-light from the torch.
  • Students must be able to show that the light is travelling from the torch, around the full length of the baffle, and then back to the night-light.
  • Any solution to short-circuit the path around the full length


  • Student should record each change that they make and include a rough sketch of each layout


  1. Each student must draw and label one diagram of any of the layouts that were completed by their group.
  2. Each student must create a 'ray diagram' showing how the light travels around the loop for the layout that they have chosen in item #1 above (the previous item)
  3. What principles of light transmission were used: reflection, refraction and/or other?
  4. Is there a better way to send light around in a loop?


  1. If repeating the experiment, would you do things differently
  2. Do you know of any measuring device where measurements depend on light travelling in a loop?

Write down your answers.

Example - How Light Travels (BBC interactive experiments & results):

In your class/group discussions, describe some everyday situations where, how and why people, plants and animals use light and shadow.

Complete the on-line interactive tasks to predict, observe and record the effects of shining light on a variety of everyday objects.

Light & Dark:

Light things up

1. Light & Dark - Light & Dark: Drag different things into the centre of a dark room:

1. Does the candle shine the same amount of light as the torch?
2. Does the candle shine the same amount of light everywhere in the room?
3. Does the torch shine the same amount of light everywhere in the room?

How We See Things:

BBC How we see things

3. How We See Things - Drag different angled mirrors into the path of the light:

Follow the instructions: Enter your answer below:
1. What happens when you drag a mirror onto the light (drag first, then click)?
2. Can you select the correct mirror to reflect & re-direct the light beam onto the tent?
3. How many mirrors do you need to direct the light beam onto the bench?
4. Can you direct the beam onto the dog & then the bench by only changing one mirror?
5. How many mirrors do you need to direct the light beam onto the balloon stall?
6. Press the 'QUIZ' button. How many answers can you get right?


Blecha, Gega, & Green, 1979, p. 154
learn/light/stage3-pd/page-03/home.txt ยท Last modified: 21/12/2016/ 19:00 by