Two weeks after an Edmonton high school teacher said he was suspended, Lynden Dorval told CTV News why it happened, and why he kept giving zeroes to some students, even after he was told to stop.

Dorval teaches physics at Ross Sheppard Composite High School, and doesn't agree with a directive called the ‘Behavioural Code System' introduced at the school about a year and a half ago that was meant to replace marks of zero with assigning behaviour codes for formative assessments.

"Our marks program doesn't recognize anything that isn't numerical," Dorval, a public school teacher for 35 years said. "So of course the student's marks are only based on the work they have actually done."

"It's just like in real life, there are always consequences for not doing things."

In a letter from Principal Ron Bradley to the Edmonton Public School Board, Brad asked for a replacement teacher, after a series of incidents involving Dorval.

The letter cites three incidents where Dorval reportedly went against policy, assigning his students a mark of zero instead of ‘behaviour codes' – the first dated back to November 2011, then on April 13, 2012, and then again on April 18.

Initially, the principal says he had discovered Dorval was assigning zeroes – then on April 13, Bradley said he had discovered again that the teacher was giving zeroes, the letter goes on to outline a meeting where the principal told Dorval to remove the zeroes, and replace them with the behaviour codes.

In the most recent incident, the teacher was reportedly found to have removed the codes, and replaced them with zeroes.

The Edmonton Public School Board would not confirm the reasons behind Dorval's suspension.

Dorval said the zeroes he gave to students were not permanent, and they are important for students to learn about the ‘real world'.

"I think it makes the student accountable," Dorval said in an interview with CTV News. "The students know that in my case they're not permanent zeroes, it's just an indicator that they have to do something about it because this is how their mark is going to turn out if they don't."

The superintendent for the Edmonton Public School Board said teachers working for the public school board are expected to follow assessment plans.

"When an assessment plan has been put in place at a school level, it's my expectation that every staff member will stick to that plan," Superintendent Edgar Schmidt said.

Dorval has three weeks from the date of his suspension to appeal the board's suspension, action he says he plans to take.

With files from Veronica Jubinville