The Calgary Board of Education (CBE) called police after parents of a seven-year-old student reported the alleged Oct. 24 assault to school officials.
On Wednesday, Chi Shing Tam, also known as Simon Tam, 62, of Calgary was charged with sexual assault and sexual interference with a child under 16 years old.
He has no criminal history.
Police said the assault was very brief, likely lasting seconds, and happened in a secluded area during school hours.
To protect the victim, they are not revealing the of the school.
It is also believed to be an isolated incident.
Staff Sgt. Stephen Johnston said police were pleased the school did the right thing and contacted them.
"Any sex assault on a child is very concerning to us," he said.
Jonhston said many charged with sex offences against children do not have prior records.
He also said the case should serve as a reminder of why it's important for parents to keep open the lines of communication with children.
"Listen to your children when they come home and talk about they day at school," he said.
CBE spokesman Richard Pete said resources are available at Connect Family and Sexual Abuse Network, at www.connectnetwork.ca, 1-877-237-5888 or 403-237-5888, and Calgary Communities Against Sexual Abuse at www.calgarycasa.com, 1-877-237-5888 or 403-237-5888.
"When issues like this happen, I think it causes all of us to pause and wonder what this might mean for our own kids," he said.
"On the CBE website, we've published a couple local, credible resources if parents want to learn about what to look for if they ever have a concern about this."