The other day we tried working out the density of rocks but it didn’t really work -the whole problem of two variables not one and so I thought I’d revise our density experiment but re-brand it as dom dom dom the “density cake experiment…”

Helena likes to make these things we call microwave potions, my only stipulation is that if she is using food to make these she HAS to eat them. At playcentre there was often the debate about using food for play – quite a logical concern if there is any food scarcity, or if you have seen the results of over-harvesting such as the Maori did in NZ, or if like me you see stuff as the result of it’s parts (the farm that produced the wheat, the labour of the people that harvested it etc). These potions involve flour, water and food colouring mainly but briefly stretched to include a rising agent until there was the episode with too much rising agent. We also used to do a thing at playcentre – the beautiful pouring in of 1) Syrup (fake maple? whatever you have), 2) coloured water, 3) oil and then you put in washed objects and see where they end up floating…..  remove objects add flour, baking soda or some such and put in cup cake things – kids eat it! green blue doesn’t seem to matter…

Today’s was a combination and a total step up thanks to an excellent purchase at a charity shop of a digital scale. Measuring, Variables, Observation, Results and cake.

• 1/4 of a cup of syrup weighs 83g,
• 1/4 of a cup of red water weighs 59g as does 1/4 cup of milk,
• 1/4 of a cup of oil weighs 53g.

We wrote our results DIRECTLY on the bench. We achieved the classic beautiful stripes and then added the new ingredient of a berocca tablet (probably Mum’s and she’s been dead 3 years) which just happened to be on the shelf. Then we had foaming potion… the tablet floated on the syrup and the C02 bubbles made a beautiful fountain in the now pink milk and up through the oil, Helena ate the scum that floated to the top. Then half a cup (I think) of flour, mix and microwave for er 2ish minutes.

This made a totally palatable cake according to my father and I, but not so to the chemist. I suspect that Helena will be slaving over the ultimate potion recipe tomorrow and hopefully the out of date berocca will get used up and I won’t have to make lunch.

As a bonus we when we went to the Observatory this evening and saw Saturn we were told that Saturn has such a low density it would float on the sea…..