🥛 Magic Milk
Drop food colouring into milk, touch it with a soap-coated cotton swab, and watch an explosive burst of colour!
🧰 What you need
🔬 Steps
- 1
Pour enough whole milk to cover the bottom of the plate.
💡 Whole (full-fat) milk works best — the fat molecules are what react with the soap. - 2
Add drops of four different food colours in different spots near the center.
- 3
Dip the tip of a cotton swab in dish soap.
- 4
Touch the soapy swab gently to the center of the milk — watch the explosion of colour!
💡 Try touching different spots, or dipping the swab again for more movement. You can also try moving the swab slowly.
🧠 The Science
Milk is mostly water with fat molecules floating throughout it. Water molecules naturally hold onto each other at the surface — this is called surface tension. When you add dish soap, it breaks that surface tension violently. The fat molecules in the milk also react with the soap, and the sudden rush of molecules away from the soap drags the food colouring with them in swirling patterns. This is why soap cleans grease — it breaks up fat and water's reluctance to mix!
📚 Related Lessons
- 🌊 Water Around Us — Water covers most of Earth — in oceans, rivers, lakes, rain, and underground wells!
- 💧 Uses of Water — We use water for drinking, cooking, cleaning, farming, and every living thing needs it to survive!