The toilets are crowded with girls breaking the school's mobile phone ban and trying to ring their families. In art the children have stopped painting to stare at the interactive whiteboard, which shows live TV reports of the events unfolding only a few miles away.
These are among pupils' memories of being in London schools on this date last year, when Britain's first suicide bombers killed 52 people and injured 800 others.
Schools across the country will today take part in a two-minute silence at noon to commemorate the attacks on July 7, 2005.
The event is also being marked by That Summer Day, a BBC drama based on interviews with dozens of London pupils who feared for their parents'
The drama is fictional, but the comprehensive where it was filmed, Islington Green, has a real-life connection to the events.
Alice Clay, its assistant head, was one of the few passengers to escape without any injuries from the carriage next to the one on which the Aldgate tube bomb was detonated.
Ms Clay, 32, has been holding special assemblies this week. She has described to pupils what it was like during the 45-minute wait underground.
At the time she thought she might die and how later she felt guilty that she could not help fellow passengers.
"There was a loud bang - I thought it was a bomb from seeing films - then it went black, there was a lot of smoke, then a reddish light from the emergency lights," she said. "I don't tell the pupils about everything I saw because some of them are very young. But I describe how I no longer feel angry, and instead have felt sad."
The ways schools responded varied. Most followed emergency procedures, keeping pupils indoors until their parents collected them. Sir John Cass primary near Aldgate tube station was forced to evacuate children and staff. Some schools kept pupils informed and allowed them to watch television news, others decided allowed the information to slip out as the day progressed.
Hannah Pescod, the producer of the TV drama, said that one of the Year 8 girls she interviewed had told classmates: "France has bombed us because we got the Olympics."
"The other pupils laughed when she said it," Ms Pescod said. "But when I went on to the next school they said that they had believed the same rumour."
Several scenes are taken directly from pupils' accounts, including the queues of anxious pupils outside heads' offices waiting to use telephones.
A key incident in which a bus driver refuses to allow a burkha-wearing girl on board, was a real event described by the pupils, although it occured a few weeks before the bombings.
That Summer Day is on BBC2 today at 4.30pm