Fairy light box

If you celebrate Christmas, I hope you had a good one.  Our plans were somewhat curtailed by lockdown restrictions, but the boys had a lovely time at home.  Whilst their new presents are providing welcome entertainment, I thought I'd post another activity we tried before Christmas, but which would work just as well now.  

Last year my then three year old and I played with coloured lights and shadows, but I wanted something which would work for my toddler to explore colour mixing and which was easier to explain.  I therefore went with a very simple setup - some white LED fairy lights inside a clear plastic box with some white paper sellotaped inside it to diffuse the light. I made some coloured filters by sticking primary coloured (red, blue, yellow) acetate glued in some cardboard frames.  We've had a few games where the pieces pop out of a cardboard surround and I kept these and used them for this which made the frames robust.  Coloured cellophane e.g. from sweet wrappers and cereal packets would work too, but may not last as long!

Colour mixing on the light box

I switched the lights on and placed the red, blue and yellow filters on the box.  I suggested that my son tried placing them on top of each other, and he had a go.  He was excited to find he could see green, then black when he layered up yellow and blue then red on top.  I helped him arrange them to make orange and also purple.  His brother showed him how to make all the primary and secondary colours (and black) at the same time with smaller overlaps. 

One of my son's creations with green and orange

It didn't entertain him for long (maybe 5 minutes!), but he realised that he could make new colours with pairs of the primary colours, and he happily told us which colours he made.  He did come back to it later when it was a little darker and have another go, carefully layering the filters in different orders, presumably experimenting to see if it affected the mixed colour (it doesn't, the filters each block some wavelengths of light and what you see is the wavelengths that pass through all the filters).  


  1. Once he's got the hang of this, the similar activity with polarising film is good fun.

    1. I keep thinking I've got some hanging around the house, but I haven't yet located it...!


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