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KS1 Science at Home: Week 1

An experiment to try.....

This experiment is about something called ‘surface tension’ and miscibility!

It works because the molecules in the milk stick together, making a force on the top of the water called surface tension.

It also explains why the food colouring stays together when you drop it onto the milk.

The milk and food colours don’t mix together at this stage because they are immiscible.

However, when you add the soap it breaks the surface tension and enables the colours to spread out!

Here is a link to watch the experiment. Click here                                                      

Materials you need

  • A bowl
  • ½ cup of milk
  • Washing up liquid
  • Cotton swab
  • Food Colouring, more than one colour
  • Pepper (optional)


1. Pour the milk into the bowl. Be careful not to move the bowl, you want the milk as still as possible.


2. Put one drop of each colour in different places in the milk.


3. Put just a tiny amount of soap on the end of the cotton swab, then touch it to one of the colours. WOW!


4. To clean up, just pour the milk down the drain (do not drink it).

Some Research for next week

What happens if you ‘mix’ liquids with different densities?

We will answer this question with next week’s science experiment!

What is Density?

the amount of ‘stuff’ in a certain volume of a material. Substances that are more dense than water will sink, substances less dense than water will float.