A Toronto-area mother says her son was exposed to what she describes as sexually explicit video while he played on a school-issued computer.

The boy’s mother, who did not want to be identified, says her son, a grade 5 student at Palermo Public School in Oakville, Ont., was playing a video game on a school-issued laptop last week when graphic, sexually explicit pornography popped up on the screen. It remained on the screen for nearly one minute, she said he told her.

“I was appalled,” the mother said in an interview with CTV Toronto. “I said this to the school board: ‘I want to understand how you can work with me or how you can expect me to work with my son, who just turned 10 in December, to unsee what he saw.”

She added her son was crying when he told her what happened. He didn’t understand what he was looking at, she said, and believed that he would get into trouble. The mother called the school right away, and Halton District School Board has launched an investigation.

It appears the computer network content filters used to protect the students from graphic content don’t always catch material that may surface when students are playing a video game online.

“Filtering is not 100 per cent effective for our schools,” said Gordon Truffen, superintendent of education at the Halton District School Board. “Our vendor is constantly updating, reviewing and categorizing website and adding to what’s on … our blocked websites.”

The board says it’s checking IP addresses and login information to see if the filter failed.

But the boy’s mother says she’s “in shock” that such content could slip through the cracks.

“There are many corporations, whether it be private or public sector, where employees can’t even go on YouTube,” the mother says. “So, how is my 10-year-old … having hard-core pornography come up in the classroom?”

The board says the investigation is ongoing.

With a report by CTV Toronto’s John Musselman