What I love about this Swirling Milk (or magic milk) experiment is that it takes only minutes to set up, and it uses everyday items that you probably already have at home. It’s a fun and easy experiment for toddlers and preschoolers, and you can introduce colour mixing concepts to extend it for school kids.
To do the Swirling Milk experiment, you need:
- full cream milk
- dishwashing liquid (washing-up liquid or dish soap)
- food colouring
- shallow bowl
- small bowl
- paint brush (optional)
- pipettes (optional)
What to do
1. Pour a small amount of dishwashing liquid into the small bowl. Pour milk into a larger shallow bowl, until about 1cm deep.
2. Add small drops of food colouring to the milk.
This is easier if you have pipettes or food colouring with droppers – that way kids can help. It’s fun and great for fine motor skills. 🙂
3. Dab a drop of dishwashing liquid to the colourful areas of the milk, and watch the milk swirl!
We used paint brushes to lightly dab on a drop of dishwashing liquid.
Look for two reactions. The first is the instantaneous repelling of the milk (and food colouring) away from where the dishwashing liquid drop initially touched. It’s like a growing white circle with a circumference of colour!
The second reaction is a beautiful swirling motion that you can see a few moments later. It looks like the milk and colours are dancing.
If your milk stops swirling, try adding another touch of dishwashing liquid. You’ll probably be able to start the reaction all over again.
The science behind the Swirling Milk experiment
Milk contains water and fat (among other things). Dishwashing liquid is made up of micelle molecules that are in part hydrophilic (water-loving) and hydrophobic (water-repelling).
When you add dishwashing liquid to milk, two things happen. Firstly it lowers the surface tension of the milk (making it easier for the food colouring to flow around). Secondly, the hydrophilic part of the detergent molecule dissolves in the milk ‘water’, whilst the hydrophobic part is attracted to the milk fat.
The ‘swirling milk’ effect is the race for the hydrophobic part of the dishwashing liquid to pair up with the fat globules in the milk, pushing aside everything else. The food colouring in itself doesn’t contribute to this process, but it allows us to see what is going on.
This is an easy science experiment for toddlers and preschoolers. Bumble was 2 years and 10 months old here, and she loved doing this (over and over again)! You can also extend the activity for kindergarteners, with colour mixing concepts by using two primary colours to create a secondary colour.
The photos don’t do this experiment justice. The milk is constantly moving, creating new swirls and colour combinations. It’s really pretty!
The ingredients used here are non-toxic and safe for young kids to touch, but dishwashing liquid is obviously not meant to be tasted. All kids’ activities on this blog require attentive adult supervision. Parents and carers will need to judge whether a particular activity is appropriate their child’s age and skill level. Click here for more information.
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