While I was pregnant with Cakes I was working for a chemical free childcare service. I thought if centres can do it so can I and had gotten rid of all our cleaning products and stocked up on bi carbonate soda, vinegar and detergent. As I don't clean very often we still have an ample supply some 2 and a bit years later. I had seen some bi carb and vinegar art on Pinterest (and for the life of me cannot find it now) and thought this would be a great way for Cakes to continue her obssession with colours and experience some extra fun along the way.
I spread a layer of bi carb across a small baking tray (that really doesn't get used for baking), just about half the depth. I made up three pots of primary coloured vinegar. As I did not have any eye droppers we used medicine plungers. These were a little harder for her to use though as she had to use to hands to pull the plunger out and two hands to push it back in. She mastered it, well eventually. She occasionally pushed into the pot and tried pulling in the bi carb but overall she worked it out. Cakes excitedly called out the name of each colour as she plunged it onto the bi card and laughed at the fizzle. Once most of the tray was covered she continued to drop colours on top and exclaimed the new colour made. After a few goes of this she predicted what colours she would make. She improved at naming which primary colours make which secondary colours in the short time she completed the activity. Once the bi carb was saturated and it no longer fizzled Cakes decided to roll the bi carb into balls. She did this for almost as long as she did the painting. We left the bi carb balls on the try to dry and decided we would find a use for them later in the day.
As there was a bit of a mess left over when we had finished Cakes went and got a cloth and proceeded to clean the floor. This was a long and tedious process as the bi carb when spread initially made more of a mess. Once she was calm and could see she was making progress she continued to clean and left the area cleaner than it was before we started.