Yesterday in Year 3, the children carried out a range of practical experiments in order to help them answer the following question: which substance is the most effective at cleaning coins? First, they were recapped on a range of words such as “substance”, “acid” and “alkaline”, before exploring how to measure a substance’s pH level through the use of litmus paper and a pH scale. Next, they discussed the question: “how do we make a test fair?”, and as a class, agreed on the importance of measuring out the same amount of each substance, as well as making use of the same measuring container when collecting a particular substance.

They then set to work setting up their experiments by gathering the equipment they required and measuring out the different substances (soapy water, vinegar, cola and tomato sauce), before investigating the pH level of each one through the use of a pH indicator pack. Once they had tested each substance and recorded their results in a table, they then submerged a one pence coin in each of the substances on their table, then carried out four observations across a twenty minute period i.e. five minute intervals. Once the time was up, each table removed their coins from the substances and examined the results. They discovered that acidic substances are the most effective at cleaning coins, particularly tomato sauce.

Take a look for yourself…