In Second Year Primary, the children are studying plants. So, they have grown cress heads. Cress is a plant that the English eat a lot in salads and egg sandwiches. It grows quite quickly, so the children have seen them sprout and grow to the point where they can eat them in a matter of days.
Learning about plants is much more fun and motivating if students actually grow something. They have put the soil in the pots, then put the seeds in, and then watered them so that they grow. And then they took them home, and could try eating the cress if they wanted to.