Nicola Sturgeon has ordered schools in Scotland to cancel plans to allow 15 to 18-year-olds into classes to complete coursework.

Numerous secondary schools, including in areas such as Perth and Kinross, Falkirk, Bishopbriggs and North Ayrshire, told pupils on Friday and Saturday they were expected to attend school on Monday to finish essential coursework.

Private schools are also asking pupils to return to resit their preliminary exams, similar to mocks in England, after John Swinney, the deputy first minister, announced the cancellation of exams in Scotland on Thursday.

On Sunday, Sturgeon said that allowing large number of pupils in schools undermined the strict social distancing advice she issued on Friday, which led to pubs, clubs and gyms being closed. “We simply cannot have too many people in our schools and nurseries,” she said.

Coursework would now need to be done remotely and the Scottish Qualifications Authority, which runs the country’s exams system, would soon set out how qualification grades would be assessed, the first minister said.

Sturgeon also disclosed there had been 10 deaths in Scotland so far, an increase of three on Saturday, and 416 positive cases, up by 43 in 24 hours. She said the NHS had needed to call on the military to help transport a patient from an island for treatment on Sunday.

“This underlines the fact that no part of our country will not be affected by coronavirus,” she said.

Sturgeon added that after a surge in the number of non-residents fleeing to Scottish islands to holiday homes or caravan parks, an existing clampdown on ferry travel to the islands had been tightened.

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CalMac, the country’s main ferry firm, announced last week it would take no new bookings until July. Sturgeon said from now on ferry companies would only take bookings for essential travel to the islands but would take visitors off immediately. She also asked the country’s hotels and B&Bs to stop taking bookings.

“It may well be an understandable human instinct to think we can outrun a virus but the fact is we can’t,” she said. “What we risk doing is taking it where we go and in rural communities that means extra pressure on health services that are already more distant from people.”

She said schools still had an essential role to play to look after the most vulnerable children or those whose parents were key workers. A list of occupations that would get priority was being circulated soon, but intensive care unit nursing staff and critical care specialists were at the top of it.

Catherine Calderwood, Scotland’s chief medical officer, said epidemiologists now estimated that an infected person could infect between four to six people, twice as many as previously thought. That could lead to “an explosion of cases”, she said.

Police Scotland said they had issued emergency closure orders to a number of pubs that had defied instruction to close on Friday night, and would be reporting them to licensing authorities. There were reports of landlords in Glasgow, Greenock and Lanarkshire serving customers until forced to stop.

Deputy chief constable Malcolm Graham said: “This is absolutely reckless and endangers not only the lives of customers but wider communities in an extremely fast-moving and unprecedented situation where both the health and safety of the nation is at stake.”

Sturgeon said the police would also get emergency powers, which will be introduced on public health grounds later this week. “Last night a tiny minority of pubs remained open,” she said. “Let me be blunt: in doing so, they put lives at risk. My message to them is close now. We will have emergency powers within days and we will use these powers if we have to.”