The same as we give everyone else a test.
It's going to be shit. I don't think I'm being negative without a 'can do' attitude or whatever it is that teachers area always being told on here. This is realistic.
Your children will be in 'bubbles'. This might be a bubble of 30 (so, one class), it might be a bubble of 300 or more (year group in secondary for example). Those children will be mixing freely with each other, with no social distancing, or very little. Adults will try to keep their distance, but this is impossible in primary school. No one is allowed to wear a mask or visor (although some schools are allowing this).
If a child has symptoms, they have to go and get a test. In that time, they need to isolate - so that's one parent too. If that test is positive, then things will be looked at in the bubble to try and keep children further apart. The bubble doesn't close on this basis, it only closes with 2 confirmed positive tests. When there is a second confirmed case, PHE work with the school to decide if there have been enough 'close contact' issues to get the whole bubble to isolate for 14 days. This will be teaching staff and all children. This has an impact on family members, obviously for childcare, but if your child is a positive, then your family isolate. The child for 7 days, family for 14. In theory, the child could come back to school if symptom free and 'well' after 7 days, but there won't be a bubble for them to go in to if there has been another confirmed case.
At this point, online learning picks up straight away. Schools will have to have this up and going v. quickly just in case. Not sure what happens if it's the teacher who is ill - are they meant to be teaching from their beds?
Anyway. If there is a first confirmed case in your child's bubble, and it gets out on WhatsApp or FB, are you going to keep your child at home? Or are you going to send them in to gamble with maybe already having it, or being around children who already have it because of their close contact with someone who has?
Also, school itself and that whole learning thing, becomes very tricky. Children are going to be in mixed ability bubbles, with little option for intervention groups (for example), and no streaming. So children who can't read in year 3, will be with children in year 3 who are reading Harry Potter, and the teacher will somehow be expected to do catch up. Some schools are allowed other adults into other bubbles for intervention support or PPA cover, others aren't. That means there will possibly be adults working closely with your child, who are also working closely with tens of other children.
Meanwhile, anyone with a temp, a cough, a sore throat, will have to be off for a test. So they are probably missing a minimum of 2 days at a time. By November, most classes will have a significant minority of children out getting tested at any given time, creating big gaps in learning journeys. They will allegedly have to have online learning for those 2 days - but who is setting that? The teachers are still teaching, and what if they child isn't able to actually do work because they are ill? Teachers are going to be having a tricky time with that.
Ways round it? None that I can see being financed by this government, or able to be resourced in a country where teaching already has a massive retention and recruitment issue.