Many things we see produce light (lamps, candles, the sun, stars etc.) but most do not. For example, in order to read a book we need a light source. Light is reflected from the pages of the book in all directions and some of it happens to go into our eyes. An image of the page is formed on the retina and millions of light sensitive cells transmit nerve impulses to the brain where the signals are interpreted.
The safety precautions mentioned on p. 86 of the National Primary SESE Curriculum could be extended to include other potentially dangerous sources such as laser pointers and high intensity LEDs.
The role of the teacher in the learning process is vital. It is not a matter of ‘telling them the facts’ but of continually leading pupils to a deeper understanding through
- identifying pupils’ ideas
- helping pupils to articulate their ideas (discussion, writing, drawing)
- asking them questions that challenge their misunderstandings
- encouraging them to observe carefully and to reflect on what they can observe
- performing demonstrations that reinforce basic concepts
- performing demonstrations that cause pupils to modify their ideas
- training pupils to ask questions that might lead to an investigation
- facilitating pupils’ investigations
“Firsthand investigation is central to the way in which young children learn science. It equips them with the realisation that they can provide their own answers to problems and that they can learn from their interaction with things around them.” (National Primary SESE Curriculum: Teacher Guidelines, p. 2)
A common misunderstanding of vision
When asked to explain how we see things, many children (and some adults) omit any reference to a light source; some even imagine that eyes emit some kind of ‘vision rays’. Simply telling pupils that this is not so does not in itself change their ideas. It is necessary to enable them to come to a more coherent interpretation by using approaches such as the following:
- explore/discuss why we cannot see in the dark
- review and discuss earlier ideas
- differences between day and night, light and shade; how shadows form
- light comes from different sources
- light is needed in order to see
- demonstrate that white or brightly coloured things reflect light (e.g. a white page on which light is shining can illuminate a shaded area)
- allow pupils to explore the formation of images by a magnifying glass (a lens)