NASUWT General secretary Chris Keates said unions were trying to keep the action "pupil and parent friendly", such as cutting down on paperwork.
But she warned the position could change, especially after a report from the teachers' pay review body later this month.
A teacher with six years experience has lost £5,500 through a pay freeze and pension changes, while those in the job for two years had lost £3,500, she said:
Teacher morale is at an all-time low and our research shows that over half are seriously considering leaving the profession.
More top news
The business secretary called the move a 'positive step forward' after the US-imposed tariff sparked fears over jobs in Northern Ireland.
A report published by the Boundary Commission for England details plans to reduce the number of MPs by scrapping 50 constituencies.
The slump will spark scrutiny, especially as statistics show a rise in racially or religiously motivated offences following the EU vote.