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Tuesday 11th March Eggciting experiments and crazy custard. Impossible surely! The girls were set the challenge to get a shelled hard-boiled egg into a narrow necked bottle without either touching it or damaging it. Almost 100% success rate with this fascinating experiment that relies on the expansion and contraction of gases as they heat and cool. Then things got messy and the students made crazy custard. They mixed custard powder with water, making sure to stir in the water slowly so there were no lumps! The result is a strange yellow substance that will either act like a solid - if you punch it quickly, or roll it into a ball OR will act like liquid, if you touch it gently. The reason for this odd behaviour if that custard powder and water mixture is a mixture of solid particles suspended in a liquid, called a "colloid". When you stir the mixture slowly, the custard powder particles can move around in the water quite freely, and so it acts as a liquid. When you stir the mix faster or hold it in your hand tightly, the solid particles rub against each other causing friction. This makes them stick together and act like a solid. Forensic Science Dr Nicky King from Exeter University gave a fascinating interactive lecture to the Year 9 girls on Forensic Science. It enabled the pupils to use some of their existing knowledge to work through a crime scene investigation and explains some of the science behind popular dramas such as CSI. They had an overview of the techniques in forensic science and their application along with plenty of blood, bullets and drama along the way.
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