Strike at academy that is 'haemorrhaging staff'
Teachers, union members and parents have formed a picket line outside Longsands Academy in St Neots.
The National Education Union (NEU) said the school wasn't "willing to budge" on the "Morning Welcome".
Teachers feel their time could be better spent elsewhere, building a "rapport and relationship" with children.
A spokesperson for Longsands Academy said it was "truly saddening" that strike action was going ahead on the basis of "one last" issue.
The state-funded secondary school is remaining open to students while NEU strikes take place on 9 and 10 July.
Helen Brook, the union's district and branch secretary, said five hours of negotiations took place last week with the Astrea Academy Trust, which runs the school, but they were unable to come to an agreement.
The union's main concern is the school's staunch position on the Morning Welcome, which sees students lining up outside in silence to receive news and messages.
NEU members want to see it scrapped in favour of spending more time making personal connections with the children in their care.
Ms Brook said: "They are haemorrhaging staff and it cannot go on."
Astrea confirmed that 15 teachers had left this academic year and a further 21 would leave at the end of next week.
A spokesperson for Longsands Academy said it was "deeply disappointing" that industrial action was going ahead.
"We have made many compromises throughout our discussions, but we will not compromise on holding the Morning Welcome," they said.
The spokesperson said the Morning Welcome lasted five minutes and served to offer students a round-up of news for the day, positive messages and the chance to celebrate student achievement.
Earlier this year, some former teachers at the Astrea Academy Trust - which runs more than two dozen schools - came forward to say that fear and toxicity run through their schools.
Joining the picket line, physics teacher and NEU representative Sam Blake said he would soon be leaving the school after a nine-year tenure.
"I absolutely love this school and this community, but for the good of my mental health and levels of stress, I don't feel like I'm able to continue here," he said.
"It's a management that values students standing in silence in lines over students spending time with their form tutors in a kind of pastoral, caring environment."
Longsands Academy was rated "good" by schools regulator Ofsted after an inspection in February.
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