Science Experiment – Milk, food colouring and detergent.

In Room 7, yesterday, we were doing a science experiment. Mrs Hamilton poured milk and food colouring in a bowl. Each desk group was given a bowl of milk. We used yellow, pink and green food colouring. Mrs Hamilton added dishwashing liquid and the colours expanded, making the colours move to the side of the bowl.

We found out that milk and detergent (like all things in this world) are made of molecules. A molecule is something in its smallest form. Some molecules have positive and negative charges. A positive charge is attracted to a negative charge. We discussed our prior knowledge about this with magents and how they connect positve to negative and the way we place batteries positive to negative in a remote. When the detergent enters the milk, the molecules have a negative charge. The water molecules and the protein in the milk have positive charges, so when the detergent enters the milk, the negative charge races to the positive charge. The food colouring is pushed to the side as these molecules move around the milk, because the food colouring does not have any charge.

This was a complicated idea to understand so we acted out what the molecules were doing in the milk. We stuck post its on our heads with different colours for the different molecules. The protein and water were different colours to the food colouring and detergent. The point was for the detergent negatives to get past the food colouring to the protein and water positives. The food colouring got pushed to the sides. Because of this, the positives were able to connect to the negatives.

Written by Room 7 and Mrs Hamilton

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