A second teacher, who was pregnant, was punched in the stomach by a young student while at work.

"If I were a [education union] member, I'd be very disappointed at the lack of support," Ms Lee said.

"There can be … no explanation for the lack of action by the union, whose primary task is to represent their members and make sure they are working in a safe environment.

"They must have known teachers were being hurt in the work environment."

Union ACT branch secretary Glenn Fowler said the comments had distressed and disappointed the two teachers, who had worked closely with union representatives on the issue.

Both teachers were quoted in a letter demanding a retraction from Ms Lee.

"I am upset and angry that Ms Lee has misrepresented the union in the Legislative Assembly," Melanie wrote.

"The AEU has been with me from the beginning on this long dreadful journey … [after] I approached the union with my concerns, as no one was listening to me."

Mr Fowler, in the letter, accused Ms Lee of exploiting the teachers situation to score political points.

"I trust you'll agree that it is better hearing from these people themselves rather than you insensitively and erroneously attempting to speak for them, without checking the facts first with a union that has attempted to cultivate a good faith relationship with you," Mr Fowler said.

"With all due respect to the officers of WorksafeACT, it was not them that began this powerful and unprecedented change process, as you have suggested. It was the AEU.

"Had you bothered to check in with me prior to your remarks in the Assembly, we could have assisted you with the facts of the matter."