July 7 ringleader Mohammed Sidique Khan tried to radicalise one of his 11-year-old pupils, the inquest into the attacks heard today.
Khan befriended the young boy after meeting him through his job as a primary school mentor and attempted to convert him to Islam.
He introduced him to Shehzad Tanweer, his number two in planning the 2005 London bombings, and on one occasion told the child that people would "pay" for what they had done to Pakistan.
Concerns were also raised about fellow bomber Jermaine Lindsay's attempts to indoctrinate younger pupils in extremist views while he was still at school, the inquest was told.
Lindsay handed out leaflets in support of al-Qa'ida and Osama bin Laden to fellow students at Rawthorpe High School in Huddersfield.
He also took young pupils to the school library to use the computers to access jihadist websites and download inflammatory material about the Taliban and the 9/11 attacks on the US.
Lindsay, 19, told one teacher he wanted to fight in Afghanistan and even boasted of planning to join the British Army so he could kill his fellow soldiers.
Tanweer, 22, told his uncle he taught young children about Islam at the Iqra Islamic bookshop in Beeston, Leeds, which was also linked to Khan and other extremists.
And the fourth of the July 7 bombers, Hasib Hussain, 18, defaced a schoolbook with a reference to al-Qa'ida and a picture of planes crashing into the twin towers of the World Trade Centre in New York when he was just 15 or 16, the inquest heard.
Khan, 30, was employed as a youth worker from 1997 and became a learning mentor at Hillside Primary School in Beeston in March 2001, a job that required no formal qualifications.
He was assigned to help "disaffected" and "vulnerable" pupils with behavioural problems.
The coroner, Lady Justice Hallett, noted that there was nothing in Khan's past that would have stopped him working in the school.
She said: "Whatever system one had in place, it looks as if he would have got through any kind of assessment because of his background.
"He didn't have previous convictions of a kind that would have alerted anybody."
Khan was described by staff at the school as "very impressive" and was well liked by the children, teachers and parents, the inquest heard.
Acting Detective Inspector Peter Sparks, of the Metropolitan Police, said: "There were some single-parent families and he was almost like a father figure to them. That's the way it was described."
On one occasion Khan invited a friend with "fairly strong" views to come to the school to talk about the Koran, but no action was taken against him.
Khan became close to a Hillside pupil aged 11 or 12, whom he introduced to his friends and took to the Iqra bookshop, the hearing was told.
DI Sparks said Khan engaged the boy in discussions about religion and tried to persuade him to convert to Islam "on numerous occasions".
At one point while in his car Khan referred to the 9/11 attacks and said people would "pay" for what they had done to Pakistan.
The terrorist ringleader also acted as a mentor for children at the mosque in Hardy Street, Leeds, organising trips for them and arranging a grant so a gym could be installed in the basement.
Gareth Patterson, barrister for some families of those killed in the attacks, observed: "A theme that runs through much of the evidence that was assembled by the police is the fact that there appeared to be attempts by Khan to influence other young people in the community."
The inquest also heard that Khan talked about the extremist Islamist group al-Muhajiroun, which was linked to radical clerics Omar Bakri Mohammed and Abu Hamza.
DI Sparks said: "His brother thought he was testing the waters because he spoke about a group called al-Muhajiroun who are a very well known extremist group, and his brother tried to dissuade him from going along this line."
But no concerns were expressed about Khan's links to extremist groups at this time.
"In fact, a lot of the people who he worked with in the Hardy Street mosque said that he was a very, very nice young man and all the youths looked up to him, not because he was extremist, but because he was just a nice man and very well-respected," DI Sparks said.
The inquest heard that a friend of Khan's wife, Hasina Patel, told police that the bomber went to Pakistan and Afghanistan at some point before his marriage in October 2001 to learn to "shoot and fight".
Khan returned to Pakistan on November 18 2004 having made a home video in which he apparently said goodbye to his baby daughter forever, seemingly because he was planning to die fighting.
However, his wife recorded in her diary on November 26: "S rang, good news, back by February."
DI Sparks noted: "It appeared that she originally wasn't expecting to see him but now he was coming back again."
Lindsay, who was born in Jamaica but brought up by his mother in Huddersfield, converted to Islam when he was 15 or 16 and took the name of Jamal.
He alarmed a science teacher at Rawthorpe High School with his extremist opinions.
DI Sparks said: "He spoke about his beliefs and about Islam generally, but he did exhibit a lot of anti-American views and he actually told her that he wanted to go to Afghanistan to fight for the cause."
Lindsay also told a friend he wanted to perform jihad before he died and fight American troops in Iraq.
Hugo Keith QC, counsel to the inquest, commented: "It doesn't appear that he kept these views much to himself?"
DI Sparks replied: "No."
Hussain, who met Khan in around 2001, when he was just 15 or 16, through a mosque in Beeston, also raised concern among his teachers at Matthew Murray High School in Leeds.
Shortly after the 9/11 attacks he passed two fellow pupils a note which said, "You're next" in a reference to the terrorist atrocities in the US.
The July 7 2005 bombings on three Tube trains and a bus in London were the worst single terrorist atrocity on British soil.
The inquest at the Royal Courts of Justice in London was adjourned until tomorrow.Reuse content