The Physical World: Light and Reflections

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This was our last class in the series about the Physical World (linking in closely to the NSW BOSTES syllabus for Science and Technology).  I had several new children coming, and chose to split the children covering KS1 into two groups. I will cover the KS2 material with my son on another day.

I think I need to devote some more blog posts to explaining my approach to teaching science. For now, suffice to say that I try to avoid lecturing the children! Studies have shown that most children retain only a small proportion of information presented this way. Instead, I like to provide hands on activities. The children develop their fine motor skills, and we can discuss the relevant science during the activity.

This week we made our own kaleidoscopes, largely following the instructions on Mini Eco. I used the inside of toilet paper rolls as we had more of these than kitchen rolls, and they required smaller pieces of mirror.

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I tried mirrored cardboard beforehand, but I was not happy with the reflection given by these, so instead I ordered plastic mirror sheets from Educational Experience. Our kaleidoscopes may not look as neat as in the Mini Eco pictures, but I think they worked very well.

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The early class didn’t go quite as I had planned. I didn’t anticipate how much extra help the children would need to make the kaleidoscopes and I also needed to spend time cutting out circles of clear plastic, greaseproof paper and cardboard for the ends of the tubes. I am very grateful to the parents who helped me out with all these tasks. Thank you so much!

Nevertheless we still managed to discuss sources of light, transparent vs opaque objects and whether reflective objects give off their own light or not. (They don’t, but many children think they do, so it’s worth addressing that misconception in a kindly manner. You can use the moon as a good example of an object that is reflective but does not emit its own light.)

I enlisted my son’s help in the second class and it went more smoothly. I did not present any of the extension work I wanted to cover. Never mind, there is plenty you can discuss and read about if your child is interested.

For example, How Stuff Works explains how kaleidoscopes work,  and The Physics Classroom website has a very comprehensive discussion of the nature of light, including why skies are blue and sunsets are red.

Here are a few additional activities that link well with making kaleidoscopes:

  • Take two mirror squares, taped to make a kind of ‘book’, on top of a black and white diagram. Provide acetate or similar with degrees marked in 15 degree intervals, or maybe just use a protractor fixed in place. Give the children pictures and see if they can recreate those pictures with the diagram and the mirrors. (I haven’t explained this terribly well. If I get a chance, I’ll try to do this at home and post some pictures so you can see what I mean.)
  • Use angled mirrors, as above, to see how many images of an object you can create, and what angle you need to use to do this. (This is the second activity in this handout from Magnet Lab in Florida. If your child gets a partner to work with, they could also try the other one.)
  • With a glass or tank of water, powdered milk, and a polarising filter, you can explain why the sky is blue. See the San Francisco Exploratorium website for a full description of this demonstration.

Please let me know what you think of this class and my suggested extension activities. Or ask me any questions you like about light and reflections (particularly if you are interested in lasers, because I love talking about those)!

You might also be interested in an earlier blog post about how our eyes see colour.

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