Ethan had suffered from asthma since he was a toddler so Miss Kowalewski knew what to do - Ethan puffed on his inhaler, then got into the shower, which usually helped steady his breathing.
He had a quick shower then jumped out, feet still dirty, but it did not help, so Miss Kowalewski rushed him to Hawera Hospital.
He was intubated and given CPR but when that failed, Ethan was flown to Starship on Monday morning and put on life support. He died in his mother's arms on Tuesday.
"There was nothing I could have done," Miss Kowalewski said. "I couldn't have taken him any quicker, the doctors couldn't have acted any differently."
Miss Kowalewski brought him home and laid him in his bedroom for his friends and family to say goodbye. The boy's coffin was also in the house, painted in Ethan's favourite colour - fire engine red - and covered in messages from his friends.
He was farewelled by friends and family at a service at St Joseph's Catholic Church in Hawera on December 28, then buried in the family plot at Kopuatama Cemetery in Stratford.
Ethan spent his early childhood years in Tauranga. His grandparents Owen and Maree Kowalewski live in Greerton and Miss Kowalewski lived with them until she finished training as a teacher when Ethan was 4.
She got a job as at St Joseph's School in Hawera in 2010 and Ethan started his first year of school there the following year. In 2015 he was taught by mum - "Miss K" to Ethan at school.
He spent every holiday in Tauranga with his grandparents, enjoying things like gardening, reading and boogie boarding.
"He helps me in the orchard, he's my right-hand man," Mr Kowalewski said.
"He lived here the first four years of his life while Rachel did teacher training. He was our little boy. He still is."
Mr Kowalewski spent many hours with Ethan reading books and said the duo used to set up a "tent" in the living room, draping a tarpaulin over furniture and reading by torch light.
"He was a prolific reader," Kowalewski said.
Ethan was also a talented Minecraft player and one teacher at his school was excited for Ethan to be in his class because of how good he was at the game.
Mr Kowalewski taught Ethan chess: "He couldn't beat me, but he could beat everyone else. He picked it up really fast."
"He was extremely bright," Miss Kowalewski added. "Although he hated writing."
"But he gave it a go," Mrs Kowalewski said.
Ethan's form of asthma was a serious one and he usually had one or two bad attacks a year, which often resulted in a trip to hospital.
Miss Kowalewski said no one had been able to discover what caused Ethan's attacks. She never held him back from anything he wanted to do as nothing in particular seemed to trigger his asthma - he could play outside all day and not have an attack, while one could come on while sitting inside reading a book.
"He was never one to sit back and think 'I can't do this'. He would give it a go, it didn't matter what it was. I never really stopped him, I would just ask him if he had his inhaler."
Miss Kowalewski has hundreds of photographs of her last days with Ethan, as well as moulds of his hands and feet, all of which were given to the family free of charge at Starship.
She and her parents were thankful for the care and attention received at Starship, and that they were able to be there and hold Ethan's hand in his last moments.
"The whole family was with him. It starts the long journey to the grieving process. Not that any parent should be doing it," Miss Kowalewski said.
The family had always been vigilant about Ethan's asthma and wanted people to know how serious the disease could be.
"He finished school on the Thursday and five days after that he had passed," Miss Kowalewski said.
"There was just nothing that anyone could have done.
"It's just so important that people take all of their medication and go to every doctor's appointment to get checked on.
"I think people just need to be aware that it happens."
Asthma
In New Zealand, over 460,000 people take medication for asthma - this includes an estimated one in seven children and one in nine adults. For children, asthma is one of the most common causes of hospital admissions. In 2011, 69 people died from asthma in New Zealand.
- Asthma and Respiratory Foundation NZ