Parents must not mingle at the school gates after dropping off their children, a Tory minister has said.
Schools Minister Nick Gibb urged people to "go straight home" rather than chatting with other parents at drop off and pick up times, and to continue to abide by social distancing rules.
Millions of children across England returned to the classroom on Monday after schools were closed to most pupils during the third national lockdown.
The reopening of schools marks the first step of Boris Johnson's roadmap out of lockdown, with the further easing of restrictions contingent on the virus remaining under control.
The Prime Minister acknowledged on Monday that an increased risk of transmission was "inevitable" in opening up schools again.
But he added: "We all know that the education of our children is so important that the greater risk now is keeping them out of school for a day longer."
Mr Gibb warned parents to stick to the rules as schools reopen this week, as ministers watch closely for any signs that the virus is beginning to spiral again.
He told the Evening Standard: “Parents need to be very careful of socially distancing.
“Hands, face, space –that’s still the rule for parents collecting their children from school.
“And they should take their children home. The roadmap doesn't permit mixing of households at this stage.
“So we are saying that they just need to go straight home after school and keep socially distancing at the school gate as well.”
He expressed concerns about parents failing to social distance, adding: “If you want to be fair to other people – as well as to prevent you yourself from contracting the virus – it’s really important to stick to the rules as they are set out and we all need to socially distance.”
It comes as Chief Scientific Adviser Sir Patrick Vallance told MPs that reopening schools could push the virus reproduction rate - known as R - up by between 10% and 15%.
He said: "For us it's very important that you measure what you've done and we don't know what the impact of, for example schools going back, is going to be.
"And so there's an estimate from the modelling group that it could have an effect on R, between 10% and 15% increase. We don't know within that range exactly what it would be."
A recent survey by the Parent Ping app of more than 3,500 parents found that 22% were worried about large groups mingling outside schools at drop-off or pick-up times.
