Today 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 introduced to 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;  as one member of the class stressed “we wouldn’t get a substance’s true pH level if the measuring jug we use has been used to collect some of the other substances”.

They then set to work setting up their experiments by gathering the required equipment and measuring out the different substances (soapy water, vinegar, cola, toothpaste 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 two pence coin in each of the substances on their table (for the agreed time of 10 minutes). 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…