Homework never got done, which she suspects must have angered her teachers.
Perhaps they didn't know the perfectly formed waves of the Whangamata bar's peeling left-hander were providing her real homework.
"I think I was about 8 years old when I decided I wanted to be a world champion," she recalled.
"I've always kept that dream alive and have always reminded myself of that every day. I knew what I wanted, and I still know what I want - more world titles. I'm just going to keep working at it."
In November, hundreds of people gave her a hero's welcome as she was paraded through the main street of Whangamata after her surprise win in Brazil.
She hadn't expected to even make it to the championships, but she kept smiling, and kept winning.
Mum Janine and dad Dean, who took their son and daughter surfing every night after closing up the surf shop, have followed Ella all over the world this year.
In Nicaragua, their car was broken into and Dean had to beat snakes away from their hotel room door.
It all paid off in Brazil, when over two weeks Ella's steely focus helped her edge out a field of well-established surfers, including Hawaii's star, Tatiana Weston-Webb.
All of them turned up with an entourage of nutritionists and trainers.
Ella had her mum.
"I think it was a shock to everyone when I won. Everyone was like, what, the girl from New Zealand?"
She still may be the "happy girl who works in the Whangamata surf shop", but more things have come around in her life than she realises, since that wide-eyed child started taking to the surf.
She remembered how nervous she was when first paddling out to the back breakers, with her father telling her to hold on to his leg rope in the water.
A few weeks ago, she did the same for a young girl she's teaching to surf.
Since she started taking free lessons for young beginners on Thursday nights, numbers have exploded from a handful to more than 100.
"This little boy came up to me at the junior club night and told me 'my dad has been trying to get us into surfing for two years, and we've never wanted to come to the beach, and we've never really liked it, but since you won the world title, and he said you were going to be teaching us, we couldn't get here fast enough'."
The local council has offered to dedicate a seat at the beach to her.
"I'm just blown away by what has happened," she says.
And of all the famous breaks she has surfed - there are too many to name even in the last year - she still rates her hometown bar as the best of the lot.
"It's just a great feeling to be pushed along the wave ... it's all the ocean and you," she said.
"When you hop in the water, it's like half those things on land, they don't exist."
She wants to keep travelling, surfing, and winning, but for now she's happy to know that little pig-tailed girl's wish has been fulfilled.
"It's like a crazy dream, a crazy story, but it has come true ... and I'm so grateful for the support that has been behind me."
