Speaking at Saturday's Downing Street briefing, deputy chief medical officer Dr Jenny Harries explained how social distancing can work in classrooms with young children.
Dr Harries said plans include having small groups "where you increase the level of interaction a small amount, but it is contained".
The Government expects children to be able to return to nurseries and childcare settings, and for reception, year one and year six pupils to be back in school, from June 1 at the earliest.
She said: "Although it is recognised that small children will run around and interact, we expect them to, but you can still distance. I know this is the plan."
She also suggested that desks could be placed appropriate distances apart from one another to prevent long periods of close contact.
Dr Harries added: "A child rushing past another one in a normal area is probably not much of a risk.
"But if they were sitting directly opposite to each other in a very small space, close together for a long amount of time - that might be more of a risk.
"All of the interventions are designed to minimise those, while still allowing children to learn."
The deputy chief medical officer was later asked about guidance which allows children to take their own lunch boxes to school, but not their own pencil cases.
She said: "I think the thing in a children's environment is there are certain things that you can control pretty well, which might include pencil cases and things that you use routinely during education.
"By doing that, schools can provide them and ensure that they are maintained clean.
"The issue about lunch boxes is, they're quite personal to the child eating the lunch, and I can almost guarantee that one child won't want to eat the lunch of the one sitting hopefully two metres distance from them."
She added that hygiene was important for both lunchboxes and pencil cases, and stressed the need to encourage children to wash their hands before and after eating.
Dr Harries later said that recent data shows that while the infection rate is the same in children, they are less likely to get seriously ill or pass the virus on.
She said: "We think children probably have the same level of infections, we're just coming through that data now with the ONS survey, but they definitely don't get as ill.
"We very rarely see children in hospital in proportion to the older population.
"For younger children as well, evidence is still growing but there may be some evidence there that they are less likely to pass it on."
Dr Harries later added that younger children returning to school do not have some of the risks expected with older children.
She said: "If you pull back a whole load of older children, they tend to get on buses, travel longer distances, have different social interactions, and some of those social interactions are actually far more significant in moving the R-value than just going back to school."