Gavin Williamson said the new guidance was part of protective measures aimed at minimising the risk of infection when pupils and staff return to school.
The Government wants nurseries and primary schools to reopen for certain year groups from June 1, and hopes all primary pupils can receive a month of education before the end of the summer term.
More Covid-19 coverage:
South Staffordshire MP Mr Williamson was asked an urgent question in the Commons on coronavirus testing in schools.
He said: "On Monday my department published initial guidance for settings on how to begin to prepare and we’ll work with the sector leaders to develop this further in the coming weeks.
"This guidance sets out protective measures to minimise the risk of infection, including restricting class sizes and limiting mixing between groups.
"Crucially, all children and staff will have access to testing if they develop symptoms of coronavirus.
"This will enable a track-and-trace approach to be taken to any confirmed cases."
The Government has faced a backlash over plans to reopen schools, with education unions advising staff not to "engage with" preparations for the proposed return on June 1.
Nine unions, representing school leaders, teachers and support staff, have accused the Government of showing a “lack of understanding” about the dangers of the spread of coronavirus in schools.
The joint statement, published by the Trades Union Congress (TUC), warns that staff will “not be protected” by social distancing if primary schools reopen to more year groups from next month.
It says: “We call on the Government to step back from June 1 and work with us to create the conditions for a safe return to schools based on the principles and tests we have set out.”
The plea comes after the Government announced its ambition for all primary school pupils in England to go back to school for a month before the summer.
The Government said it expects children to be able to return to nurseries, and for Reception, Year 1 and Year 6 pupils to be back in school, from June 1 at the earliest.
The joint statement, from organisations including the NAHT school leaders’ union and the National Education Union (NEU), says: “We all want schools to reopen, but that should only happen when it is safe to do so.
“The Government is showing a lack of understanding about the dangers of the spread of coronavirus within schools, and outwards from schools to parents, sibling and relatives, and to the wider community.”
It comes after the Department for Education (DfE) issued guidelines on Monday which said primary school class sizes should be limited to 15 pupils and outdoor space should be utilised.
The advice, on how to safely reopen schools, calls for lunch and break times to be staggered, as well as drop-off and pick-up times, to reduce the number of pupils moving around.
On the guidance, the joint statement from the unions adds: “Uniquely, it appears, school staff will not be protected by social distancing rules.
“15 children in a class, combined with their very young age, means that classrooms of four and five-year-olds could become sources of Covid-19 transmission and spread.”
“We do not think that the Government should be posing this level of risk to our society,” it says.