Our main subject matter for the evening was ....SPYING & SECRET CODES...!
Amongst other experiments the following were included:

OPENING DEMONSTRATION EXPERIMENT,
Changing Water into Wine and back into Water! - The first glass contained a clear liquid. It was poured into the 2nd glass and it instantly changed to a red colour. This was in turn poured into the 3rd glass and instantly changed back to a clear liquid. 

The 1st glass contained water with a few drops of sodium hydroxide (caustic soda crystals). Then added a few drops of phenolphthalein to the 2nd glass. Then added a few drops of hydrochloric acid to the 3rd glass.
** How it works ** - The sodium hydroxide makes the water in the first glass alkaline. When you pour the alkaline solution onto the phenolphalein, a chemical reaction occurs, turning it deep red. When you pour the red mixture into the glass with the concentrated acid in it, the phenolphthalein returns to a colourless form - water into wine, and then back again.

INTERACTIVE - Air presure - Holding a glass tumbler upside down full of water supported only by  a piece of cardboard. Demonstrating the efefct of air pressure and surface tension.

INTERACTIVE - Exploring the magic of polymers with simple household materials.   Who would have thought that a combination of a plastic bag, some  water and a few pencils would produce such a simple dramatic experiment. We learnt how to poke a hole in a plastic bag filled with water and reseal it like magic. The secret has to do with a better understanding of the chemistry of polymers. Quote from Steve Spangler.

INTERACTIVE MAKING A CARTESIAN DIVER
'can do this at home' - controlling a tomato ketchup pack inside a bottle full of water. We filled a 2 litre coke bottle, added some salt until the pack floated. Then we were able 'to control' the pack, diving and rising.

INTERACTIVE - a touch of THE SCIENCE of SPYING & SECRET CODES
We talked about the recent news of GCHQ advertising for anyone to break the secret code they had published on the internet.
Invisible Ink - Mike had written a special code on an A4 sheet of paper using lemon juice, the code was invisible until the sheet was heated over a gas flame when it was revealed.
We mentioned other types of lquid which could be used for 'invisible writing.' We talked about a special machine called a 'LIE DETECTOR'.  A very crude type of a LIE MACHINE was set up with a multimeter, a copper handle and an aluminium handle. Different measurements were taken example 500 mv when these were grasped. Some children wanted to 'test' the machine by telling a lie but it wouldn't have been genuine!
Mike had a special radio code which is unqiue. How many seceret passwords do we have for our computers?

 


Each child made a Secret Cypher Wheel -
           how to send seceret messages to a friend.

                        Click here to go to topspysecrets.com







The December issue of 'making science cool' booklet was handed out
- click here to see pdf copy  or if children absent the booklet was posted.

In all a fantastic evening for children and helpers

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