The First Minister has warned school pupils to stop having house parties which breach Covid rules.
A number of small local coronavirus outbreaks have affected schools in Glasgow, North Lanarkshire, Renfrewshire and Perth and Kinross.
Nicola Sturgeon stressed that infections among pupils are believed to have spread outside school and are thought to be linked to indoor gatherings.
She emphasised the importance of keeping schools open to make sure more education is not lost.
Speaking at the Scottish Government’s coronavirus briefing, the FM conceded a rise in the number of pupils contracting Covid-19 was inevitable as the country continues to reopen.
The First Minister spoke about the clusters of the virus across the country, saying: “We will inevitably I think see more cases which involve school pupils in the weeks and months ahead.
“In those cases, as has happened in the ones that I’ve mentioned today, contact tracers will identify if other students or staff at schools need to isolate and will let them and their parents know.”
Sturgeon added: “Though I don’t want to alarm anybody, I do want people to take notice – in fact I need people to take notice.
“These clusters show us that these virus continue to pose a serious risk.”
She reiterated the rules on indoor social gatherings, which say no more than three households should meet at any one time, with up to eight people attending.
In addition, people from different households must keep two metres apart and follow hygiene measures like hand-washing and keeping shared surfaces clean.
The FM went on: “If the virus is present at a house party, everyone attending the party is at considerable risk of infection.”
Sturgeon said she accepted the guidelines were “not easy” to follow – but failing to do so presented “one of our biggest risks” of spreading the virus.
The latest Covid-19 figures show 19,407 people have tested positive for the virus in Scotland, up 49 from the day before.
This includes clusters linked to pubs in Aberdeen, a chicken factory in Tayside and outbreaks affecting schools in Greater Glasgow and Clyde and Lanarkshire respectively.
Renfrewshire Council said on Monday that a case had been confirmed at Todholm Primary School in Paisley, while two cases were detected in pupils in Perth and Kinross.
Cases have also affected Bannerman High School in Baillieston, Glasgow; Caldervale High School in Airdrie, and St Ambrose High School and St Andrew’s High School, both in Coatbridge.