Schools should be the last places to shut in future lockdowns, after non-essential shops, pubs and restaurants, England's children's commissioner says.
Anne Longfield says children have a right to education and, must not be an "afterthought", and that schools should be "first to open, last to close".
She says children play a smaller role in spreading Covid-19 than adults and are less likely to get ill from it.
The government says getting children back to school is a national priority.
Ms Longfield has published a briefing setting out key actions needed to ensure children are "at the heart of planning for the future".
The children's commissioner acknowledges that reducing Covid-19 transmission in the community is very important "but it should not be automatically assumed that this requires closing schools - except as a last resort".
The briefing paper calls for the regular testing of pupils and teachers so that any confirmed Covid-19 cases - and their close contacts - can be isolated "without necessarily having to send entire classes or year groups home".
It adds: "This will be particularly important in the 2020/21 winter flu season when clusters of flu could be mistaken for a Covid-19 outbreak and result in unnecessary closure or interruption."
She says the Department for Education should expand its laptop programme in the event that pupils need to work online.
Consideration should also be given to those children taking exams next summer so they are not disadvantaged, particularly in the case of extended local lockdowns.
The briefing paper warns there is risk that some children will struggle to come back to school after a period away, and that this could lead to truancy and challenging behaviour.
The DfE should closely monitor attendance and exclusion figures within areas that have experienced a local lockdown or increasing cases of Covid-19, in order to identify where further help is needed, it says.
Ms Longfield also raises concerns that children in young offender institutions and secure training centres have been spending more than 20 hours a day in their cells, family visits have been banned, and face-to-face education has stopped.
And she suggests the government holds a news conference aimed at children, giving them the chance to submit questions to press briefings, just as adults were in the previous daily briefings.
She said: "Too often during the first lockdown, children were an afterthought," adding: "If the choice has to be made in a local area about whether to keep pubs or schools open, then schools must always take priority."
Schools minister Nick Gibb told BBC Breakfast that children would be going back to school in September, "including those subject to local lockdowns".
He told BBC Breakfast: "Schools will be open for all pupils from September and we're now looking locally when we impose new restrictions and will depend on things locally."
Mother of three Joe Watson, who has been shielding due to severe asthma, says her children would love to go back to school.
"We would love them to go back to school in September, that's my absolute hope for them - they miss their friends so much.
"We're saying to them that they're probably going to go back, but at the same time, we have to keep an eye on the data and the statistics to check to see whether it's safe enough."
Lorraine Hopkinson has an 11-year-old son who is due to start secondary school in September.
"Everyday I'm looking for reassurance so I can increase that confidence to send him to school," she says.
"If we get to the beginning of September and I don't feel that all of the issues that are currently bothering me have been resolved, I may say, 'Sorry, I can't send him in.'"
However, Professor Neil Ferguson, who resigned from the government's SAGE committee, told BBC Radio 4's Today programme things were likely to get more difficult going into autumn and winter, with people spending more time indoors and the virus transmitting more efficiently in colder weather.
He said he was reasonably confident that - now we have "good enough surveillance" - transmission could be contained but said: "It will be challenging and there will be no going back to anything close to normal social interactions, at least not until we get back to next spring, potentially the availability of a vaccine."
He said while there was little risk of transmission in primary schools, secondary schools, colleges and universities posed a "risk of amplification of transmission" as older teenagers may spread the virus like adults.
Schools needed to have a plan in place on how to continue education but reduce those contacts at school based level, "perhaps through partial attendance", he added, for example with children in school one week on, one week off.
Labour leader Keir Starmer wrote in the Guardian that the "priority must be reopening schools for the new term" and urged the government to "set out a clear plan this time, not just hope for the best".
"If that means making hard decisions elsewhere, so be it: to govern is to choose."
Paul Whiteman, general secretary of school leaders' union NAHT, said: "School leaders are currently preparing their schools for all children to return in September, and are following all the government and health guidance they have been given in order to make it as safe as possible.
"But the success of September's return to school rests as much on what happens outside the school gates as within."
Teresa Heritage, vice-chairwoman of the Local Government Association's Children and Young People Board, said councils would continue to work with all schools and local partners.