Thank you so much for all your replies – they have given me a lot to think about!  Jenny, I think you are right about cognitive load, and don’t want to make it harder by introducing another layer of understanding to something that is already quite tricky to grasp for the little ones.  There are two things I need: 1. an ability to draw and 2. more knowledge about dual coding…!

I will think on this more, and let you know where we get to and how it comes together.