Glow sticks or glow bracelets etc. can be bought cheaply on the web e.g. glow glasses for 39p each – cheaper if more than 10 bought. See the safety notes!
Bright toy using LEDs or a miniature torch using a LED.
- Black bags – enough for one per group of children.
- Black cloth bags made from dense black material, for example from an old black tee shirt.
- Phosphorescent stickers – available from toy shops and stationers.
- Torch – one per group. The school could be asked to provide these or the children asked to bring them.
The bags should be approximately 20cm x 20cm or larger. Stick a selection of phosphorescent stickers at the bottom of the bag the day before the session and then keep the bags in the dark.
When the bags have been given out to the groups, ask the children to put a few small objects into the bag (e.g. a pencil sharpener). Check with the teacher before the session that suitable objects will be available or put some objects in the bags before the session.
When they look inside the bag, (one child at a time) they will hardly be able to see the objects.
Then they should shine the torch into the bag so that they can see all of the objects.
After the torch is switched off they will see the stickers glowing brightly.
Activities 14, 15, 16: Mirror Demonstration
- A large mirror to reflect light from the PPT slide – at least 50 cmx50 cm- use a household mirror
- A second large mirror – preferably plastic
Activity 17: Class experiment
For each group:
- Mirror (schools usually have mirrors which are also used in maths.)
- Block or support to keep mirror upright
- A sheet of white paper
Several CDs to hand round for the children to see the colours in the reflected light.
Diffraction grating material in the form of plastic film can be obtained from Edmunds Optics (USA) two sheets ~ 15x30 cm2, 1000 lines per mm for ~ £8 plus postage. Keep one sheet whole for demonstrations and cut the second into pieces for the children to use. (If the small pieces are framed with card they will not be lost.)
Activity 23: Colour disc demonstration
- Hand held electric food mixer or travel fan
- Blu tac
Copy the colour wheel below, print it and glue the disc to a circle of card.
I used a hand held food mixer with only one beater attached and fastened the card to it using a large lump of blu tac. (String can also be tied through small holes in the card to fasten it to the beaters or fan to ensure that the disc does not fly off at high speed.) It was possible to increase the speed slowly so that the children could see the colours blending more and more until at the highest speed the disc appeared white.
Alternatively attach the disc to the end of a travel fan or the bit of an electric drill.
Samples of coloured transparent plastic – I found that brightly coloured transparent wallets for A4 papers were suitable and much cheaper than colour filters. I chose the brightest colours and used the wallets fastened.
Collect a few large brightly coloured objects that you have available - I used posters and silk scarves. Use the slides to show that they objects look different in different colours of light.
E.g. a yellow object in red light then green light.
A blue object in red light etc.
Note - an explanation of why yellow and blue paints mix to give green
(This works for only some blues)
- Yellow paint reflects red and green light
- Some blue colours are actually blue and some green
- Mixing paints is colour subtraction
- The reflected colour is the colour that can be reflected by all the paint
- Hence green is seen.
A string of coloured Christmas-tree lights.
(You will need to check that there is a convenient mains socket before the presentation.)
Samples of coloured transparent plastic as in 26.