What: Decorating the room with “real” rainbows, made with CDs.
How: We chose a few spots by windows that get direct sunlight, and put old CDs there. The rainbows form throughout the day, moving, shrinking, appearing and disappearing with the sunbeams.
As an activity this takes no time at all, unless you do it as a discovery project (see Extras). The beauty of it is in what it does to a room that you’re spending a lot of time in. Our CDs are in our north-facing front lounge room, which is the warmest and brightest place for most of the day during winter. The rainbows brighten it even more. For us it’s purely a decorative thing, all of us love colour and find the rainbows peaceful.
Extras: And, of course, there’s heaps of things you can talk about. We went through an accidental-discovery moment, which you could set up in advance to happen if you wanted to. First we discovered one of these rainbows that had formed by accident, and had to find what was making it. That took some conversation and exploring. Then we had to get some more old CDs to try making more. When that worked, we put them in windows – but the rainbows moved! And later when we looked again one of them had disappeared! The idea that things change over time, even if we’re not watching them or even when we are, is a basic scientific idea that kids spend a bit of time learning and reinforcement never hurts. Especially the bit about how you don’t have to be afraid of change because everything *does* change.
My kids aren’t old enough for me to bother with explaining the difference between diffraction (which is how CDs make colour) and refraction (which is how rainbows make colour). It’s enough to talk about how white light is made of all the colours and if you separate them out, that’s when you see the rainbow. Kid 6 worked out for themselves that this was a bit like when they looked through Mummy’s prism. Kid 5 also happily talked about times and places they’d found rainbows. We got to talk about the colours we could see, and whether they were distinct bands or blended into each other, and how many colours we thought there were. That’s always a good conversation, because kids get drilled early on the idea that there’s seven colours in a rainbow, and there totally isn’t. ROYGBIV is just the way it was written down some three hundred years ago by an early scientist, when we named common colours differently to the way we do now (cyan, anyone?). And it’s a handy acronym for remembering the order of colours, if you want to talk about how rainbows always have their colours in the same order, but beyond that its usefulness drops off quickly. (Yes, I have opinions on colour.) Add that to how kids get all kinds of weird-coloured rainbows on their toys and clothes, especially girl clothes, and they can come up with some fascinating and funny observations. Though I still don’t have a good answer to “Why isn’t there any pink in it?”. (I tried saying that it’s just that pink is “light red”, but that didn’t wash.)