High school students and teachers are no longer required to keep face coverings on within the classroom – though they do still need to wear them in communal areas such as corridors.
Ms Somerville said the removal of masks in classrooms “signals the possibility of a brighter future where schools can regain some normality”.
However she stressed that those students and staff who choose to continue to wear face coverings would be supported to do so.
The Education Secretary said: “The last two years have been really tough for our children and young people.
“Teachers and support staff have also had to operate in a challenging environment, but all have worked incredibly hard to deliver a quality learning experience for pupils.”
She continued: “The removal of the requirement to wear face coverings in classrooms is a positive milestone – it signals the possibility of a brighter future where schools can regain some normality.
“And of course, pupils and staff who continue to choose to wear face coverings in class will be supported in doing so.”
Ms Somerville stated: “We must not forget that Covid-19 has not gone away – we all still need to be on our guard and exercise caution. Pupils and staff must still wear face coverings in communal areas and distancing rules still apply.
“The last thing I want is to have measures in place for a minute longer than is necessary, but as we have done throughout this pandemic, we will continue to be guided by scientific and expert advice.”
The removal of masks in classrooms comes at the same time as the mandatory vaccine passport scheme, which had applied to nightclubs and some large events, is also being ended.
This had required people to show their vaccine status before being allowed to enter clubs, and events such as some concerts and football matches.
Other restrictions are also due to be eased next month, with the legal requirement to wear face coverings in some settings to be ended then.