Rainbow rocket

After we'd finished baking this morning, the boy spotted an empty bottle on the draining rack and said it looked like a rocket.  I had been musing ways to make the rainbow sugar gradient work for little hands, and had thought about scaling it up so it was bigger (so any mixing of the colours mattered less).  On the spur of the moment I suggested trying to make a rainbow rocket with the bottle.  Mission accepted, we gave it a go...

This works just like the 'traffic lights in a tube', with the most dense sugar solution at the bottom.  We made 6 colours this time, all made up to 100ml with water:
- Purple - a mix of red and blue food colouring, with 5 heaped teaspoons of sugar
- Blue - blue food colouring and 4 heaped teaspoons of sugar
- Green - blue and yellow food colouring and 3 heaped teaspoons of sugar (minus a bit that didn't quite make it into the mix) in water
- Yellow - yellow food colouring and 2 heaped teaspoons of sugar
- Orange - yellow and red food colouring and 1 heaped teaspoon of sugar
- Red - red food colouring
The boy had a lot of fun mixing colours and telling me which ones we needed to put in each tube (his fingers and mine are now quite blue!) and pipetting water.  The bigger volumes meant it took quite a long time compared to the traffic lights, so it was good entertainment!

We then took our bottle (Coca Cola in our case, but plenty of clear plastic drinks bottles are roughly rocket shaped), and filled it carefully with our twisty dropper (you could also pour).  We minimised colour mixing by adding each new colour slowly down the side of the bottle, in order of the colours of the rainbow from purple through to red.  The small boy gave up after green as it was a slow process, and I finished it off for him whilst he squirted a bit more water between empty containers.  I put a bit less of the yellow, orange and red in as the bottle tapers near the top - it's 500ml total volume.

Our 'rainbow rocket'

The rocket was a success! We sang some rocket-related songs and zoomed it around the kitchen a bit without shaking it too much!  It'll be interesting to see how long it lasts as there's not a huge difference in the amount of sugar in each colour.