Members of the NASUWT will take two further days of strike action tomorrow and Thursday.
It's part of an ongoing dispute over pay, workload and working practices, and follows two previous days of strikes late last year.
The union is calling for a multi-year fully funded pay offer that addresses the real terms loss in pay.
Members also want a strategy that addresses the problems of excessive workload and working hours.
Further industrial action is planned for February 15 and 16.
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