Ann Maguire, 61, died after she was attacked during a Spanish lesson at Corpus Christi Catholic College on April 28.
At the opening of the inquest into her death, Detective Chief Inspector Nick Wallen, of West Yorkshire Police, said the teacher suffered a number of stab wounds but one to her neck, which severed her major vein, was the fatal injury.
Mr Wallen gave the only evidence at the seven-minute-long hearing at Leeds Coroner's Court yesterday.
He told Coroner David Hinchliff that the emergency services were called to Corpus Christi at 11.49am on the morning of April 28.
"They were directed to the top floor modern languages department where paramedics initially attended to Mrs Ann Maguire, who was very seriously injured having been stabbed," the officer said.
"Mrs Maguire was taken by ambulance to Leeds General Infirmary for emergency treatment.
"Sadly, she did not survive her injuries and her death was pronounced at 1.10pm."
He told the court that Home Office pathologist Brian Roger conducted a forensic post-mortem examination on the same day at Pinderfields Hospital in Wakefield. "Dr Rogers established Mrs Maguire's cause of death as shock and haemorrhage," Mr Wallen told the coroner.
"Although there were a number of stab wounds, a stab wound to her neck had severed her jugular vein and was the fatal injury."
He said a second post-mortem examination came to the same conclusion. Mr Hinchliff adjourned the inquest to a date to be fixed.
Mrs Maguire worked at Corpus Christi, in the Halton Moor area of Leeds, for more than 40 years. She was due to retire in September.
Mrs Maguire lived in the Moortown area of Leeds with her husband, who is a landscape gardener and former teacher.
She had two grown-up daughters and two nephews whom she brought up as her own sons after the death of her sister nearly 30 years ago.
A 15-year-old boy has appeared in court accused of murdering Mrs Maguire. He is remanded in custody and is due to go on trial later this year.