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Filtration Experiment

Yesterday, I did a simple home-made experiment with my children. They always ask me what products can be made from milk. After listing milk-based products, I decided to introduce them making curd by adding acid to warm milk. To separate the curd from the whey liquid I used different filtering materials (papers). My children enjoyed being part of this experiment and said that science is fun.





Strainer/paper towel/cloth

Slice of lemon

Timer (optional)


1. Prepare glasses and different filters (i.e., strainer, tissue paper, cloth).

2. Add a few lemon juice drops to the warm milk.

3. Gently stir the milk until curd is formed.

4. Pour the milk-curd solution into the glasses. Time the process (approx. 30 min).

5. Ask your child about his/her observations:

  1. What happened to milk when we added lemon juice? (chemical reaction of milk protein with acid)

  2. Why some of the filters passed milk/whey faster than the others? (pore-size of the filters)

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