In Science Primary 7 have been looking at methods of separation. They looked at distillation and filtration as ways of separating some materials and were set a challenge to separate ink particles using chromatography.
They learned that the ink separates through water at different speeds due to having different weights – this is how the patterns are created.
Their challenge was to guess the black pen I used out of 4. Most groups solved the puzzle correctly 🙂 Well done.