Nicole Christie told a fatal accident inquiry she was preparing to teach a dance class at Liberton High School in Edinburgh when she heard a loud bang.
When she went to see what had happened, she saw Keane Wallis-Bennett's body lying underneath a modesty wall.
The 12-year-old died after the wall in the PE changing room collapsed in 2014.
Miss Christie, 26, said: "I tried to move the wall off her but it was too heavy and so I called out for help.
"Some of the girls had to help us move the concrete. We couldn't get it off."
Miss Christie was giving evidence on the fourth day of the inquiry.
The Crown Office said it was in the public interest to hold an inquiry to prevent such an incident from happening again.
On Friday, Miss Christie - who no longer teaches at Liberton High School - said that there was "nothing out of the ordinary" on 1 April 2014, the day Keane died.
She said she was set to teach a dance class before the wall collapsed on Keane.
Miss Christie said that one of her pupils did not have a leotard to take part in the dance class. She was going to get her one when the incident took place.
She told the court that she helped to get Keane's classmates out of the changing room and into a nearby hall.
Miss Christie said pupils were upset at what happened and she was in shock.
The inquiry had earlier heard that pupils had leaned on the wall to change their shoes when it collapsed on top of Keane.
She added: "My first thought was I had to get them out.
"They were panicking. There was crying. They could hear the ambulance sirens.
"I couldn't tell them anything at that point and that's when the rumours started. One girl said she was leaning against the wall. I had to reassure her."
Earlier the inquiry heard a number of statements which had been given by pupils to investigators following the incident.
In one statement, a girl, who cannot be identified for legal reasons, said that she had told Miss Christie that she had seen the wall shaking before it had collapsed on Keane.
The schoolgirl told investigators that Miss Christie told her that it was fine and she did not have to worry.
When asked if she could remember being told that by the schoolgirl, Miss Christie said that the conversation never took place.
She added: "There has been absolutely no pupil at school who told me about the wall being wobbly or anything like that."
The inquiry will continue on Monday.
A PE teacher has told a court how she and a group of teenage girls tried to move a wall which had fallen on a pupil who later died from her injuries.