The students burst into laughter.
Sir Graham corrected himself: "I'm old, I'm 68."
It was clear Sir Graham, a former teacher and principal, had worked with children before as he entertained them with his humour.
The first question asked by a student was: "When your contract ran out with the All Blacks, why didn't you make a new one?"
Sir Graham, who coached 140 test matches, said it was because he had had "quite enough".
"I was old," he added and got his audience laughing again.
"Raewyn had had enough, my mother had had enough, my kids had had enough, and I thought it might be time I'd had enough. It puts a lot of pressure on the people who you're close to, because they have no control over the team."
Some questions asked were not so complex. One girl asked what many females around the country would like to.
"Do you have Sonny Bill's number?" Everyone started laughing, including Sir Graham.
"Yeah, I have. Why? If you've got lots of money, I'll give you it later," he said.
Despite being a former coach of the All Blacks, some students did not let that get in the way of voicing their opinions. When asked what his favourite fruit was, Sir Graham replied: "Probably apricots from Central Otago. How does that sound?"
"Gross," the student replied.
Talks with Ted, run by the Farmlands co-operative, is a series of talks being held nationally to give shareholders and schools the opportunity to listen to Sir Graham while also raising money for charity.
"I talk about what I did in the All Blacks and how that relates to farming. We try go into rural schools around New Zealand and talk to them too."
Sir Graham said he had a "really good" morning at Tauraroa school, adding he had not been asked for Sonny Bill's number before.
"They were good kids. I talk to kids a lot and it's great, because they're themselves, and that's the most important thing," he said.
Last night, Sir Graham also talked at the Kamo Club, raising money for suicide-prevention charity Choose Life.