Former Ombudsman Mel Smith will conduct the inquiry, which will also look into how the system can be strengthened. He is due to report back by the end of April.
The mother of the latest victim told APNZ that she welcomes the inclusion.
But she said she would like to know how any teacher with convictions for sex crimes could be put in a position of trust.
"I just would never trust him with a young girl again.''
She said education authorities should look at what safety mechanisms are in place to stop that happening.
"The risk is just way too high. Even with rehabilitation, they should never be put in there again.''
Education Minister Hekia Parata said she has a "huge amount'' of sympathy for the family.
"I am extremely concerned about this allegation and have demanded an explanation from the Teachers Council. I can assure you this will be incorporated into the Ministerial Enquiry.''
She said it was important to remember that the employment decision was made by the school's board of trustees who were aware of the facts.
Yesterday the principal defended the school's action.
The principal, who cannot be named, said 21 years had passed since the man committed the crimes, he had not reoffended and was well respected by students and staff.
Asked if he had any concerns, he said: "Not an ounce for this man, not an ounce.''
The principal said some parents knew of the teacher's convictions but they had not been "advertised''.
"He's led an exemplary life for the last 21 years, fully recognising what he did was totally wrong. He's turned around and done everything right.''