That was my first thought too; but, with smaller numbers like that it is much more manageable to keep an eye out for symptoms and implement quarantine. Also, fr

That was my first thought too; but, with smaller numbers like that it is much more manageable to keep an eye out for symptoms and implement quarantine. Also, from a simplistic maths point of view, in a classroom with 20-30 children, with each child having an infection vector from each other child, so a 16-27x higher chance of being infected than in a classroom of 3-4.