This is entirely my little brother's idea. It's a great way to keep kids busy for at least half an hour, the project is educational in many ways, and can be used as a classroom project for 3-6 year olds.

Most children like mixing, smearing and pouring, so the project includes quite a lot of this.

The photos also are little Leva's contribution, so excuse them:).

Step 1: The Solution.

Take a jar with water and pour some oil in it, showing that water and oil don't mix and oil is on top of the water.. Shake the jar a bit to see how oil floats around in bubbles. We also added some washing up liquid and salt to see if we can make an emulsion.
Leva loves "cooking" with everything he can get to.
Allow lots of experiment - try adding things in different concentrations or adding some new ingredients - honey, or vinegar, or flour...

Step 2: Find the Medium

Try different paper - we found out that the thick watercolour type suits best, try finger-painting, potato-stamping - something unusual.
We used a little plastic cap from some medicine.