"All strikes will do is disrupt parents' lives, hold back children's education and damage the reputation of the profession," the spokeswoman said.
The first regional walkout took place in the North West on June 27, and further strikes are expected to take place on October 17 in the North East, South East, South West and London.
Plans for a national one-day walkout before Christmas have also been announced by the two unions.
Today's action comes in the same week that workers in crown post offices went on strike in a row over jobs, pay and closures. Strike threats also remain within the fire brigade and over Royal Mail privatisation.