Penny Oleksiakā€™s high school coaches are surprised but proud that their tenth-grade student has won not one but four medals in Rio de Janeiro ā€“ a record haul for a Canadian at a Summer Games.

Bryan McAlpine, head coach at Monarch Park Collegiate in Toronto, told reporters Friday that he and fellow teachers thought she Oleksiak was incredible, but despite seeing her build ā€œmore and more momentumā€ before the Games, they ā€œnever would have predicted anything like this.ā€

ā€œI thought ā€¦ maybe Tokyo?ā€ he said, referring to the 2020 Olympics host city. ā€œBut gold in Rio is mindboggling.ā€

Oleksiak tied for gold in the 100-metre freestyle Friday, after earlier taking a silver in the 100-metre fly and bronzes in the and bronzes in the 4x100 and 4x200 freestyle relays.

While he didnā€™t predict the medals, McAlpine said he was astonished by Oleksiakā€™s endurance when training at school. He said the girl once held a plank so long he had to stop her because they ran out of time.

Oleksiak would train with her national coach in the mornings and McAlpine said he worried intense fitness training at school might hurt her, but Oleksiakā€™s father told him ā€œshe can take it -- push her.ā€

McAlpine described Oleksiak as well-grounded and humble, and described how she blushed when her classmates applauded her for setting a new Canadian record at a meet.

Jenna Grezela, who coaches the swim team at Monarch Park and serves as Oleksiakā€™s guidance counsellor, told Ā鶹“«Ć½ Channel that watching her swim was like nothing she had ever seen before.

ā€œItā€™s almost like she floats on top of the water as she motors across,ā€ she said.

Grezela added that Oleksiak made time for her high school swim team even though she spent mornings training with the national team in another part of the city.

Grezela said her student also managed to balance her social life with school and athletics.

ā€œSheā€™s a high school student as well as competing at the Olympics. That doesnā€™t happen a lot,ā€ she said. ā€œTo make that work shows how humble and amazing she is.ā€