To avoid confusion.
It is NOT compulsory for key workers’ children to attend school this week. It is NOT an option for children to dip in and out of. It is an emergency childcare provision, and if students can be left at home safely because there is adequate care or they are old and responsible enough, this is what must happen. The whole point is to reduce the spread of transmission. Therefore, schools are “open” but literally want to support the minimum number of students so that we have to deploy the minimum level of staff, and expose the minimum number of people to risk.