"They were too scared to say 'we don't want to hear this."'
Ms Sim's daughter remains at the school, but another couple have withdrawn their child in protest. Other parents have told the Greymouth Star they are also considering removing their children.
Principal Bevan Clark said although the programme was in line with what was provided nationally, it had been put on hold following a complaint.
"Sexuality education is part of the national curriculum and the programme was planned using the curriculum and delivered accordingly."
Mr Clark said he could not discuss the content of the Blaketown lesson because it was an "employment issue".
"As soon as the complaint was laid we stopped the programme cold," Mr Clark said.
Ms Sim said no other adult was present when the female teacher led the class, and she was upset the teacher had carried on despite signs of discomfort from some children.
"Never once did she think 'they don't need to hear this'."
Ms Sim said the content discussed was "well above the students' level of maturity".
"As a parent we sign a consent form expecting our children to be taught the basics."
Another mother, Joanne McKay, said she removed her daughter from the school after a similar event about four years ago.
"I thought I might have been overreacting ... but I talked to my teenage children and they were shocked at what had been said - they didn't even get taught that at high school."
Another parent, who wanted to remain anonymous because she still had children at Blaketown School, said she was "absolutely disgusted" by what had happened.
She only found out when another parent told her.
"My impression from the letter was it was going to be taught by a health professional. If there were inappropriate questions, the teacher should have said 'it's not my place to answer this'. It has completely divided the school."
Board of trustees chairwoman Robyn Larking said notices in the school newsletter informed parents of the programme and gave them the chance to discuss and view the content.
"And they have the option of withdrawing their children from the programme if they wish," Miss Larking said.
The school had reviewed its policies and would survey parents before the programme was reintroduced.
She and the principal said the complaint had been addressed.
"It was taken seriously by the board and we sought advice from the School Trustees Association," Mr Clark said.
"We followed our policies and procedures when looking into this. We also followed advice from staff and other responsible agencies. We worked through a process, we've concluded a process and the board is satisfied that the issue has been dealt with."
Ms Sim said she remained concerned that pupils had not been talked to about what happened and they now had a misconception about sexuality.
She did not hold a grudge against the school but was upset the teacher had not apologised.
grey nm cr