French President Emmanuel Macron has paid tribute to "quiet hero" Samuel Paty, the teacher who was beheaded last Friday.
Mr Paty was targeted close to his school near Paris for showing cartoons of the Prophet Muhammad in class.
His killer, 18-year-old Abdullakh Anzorov, was shot dead by police.
Speaking at a televised memorial service on Wednesday, Mr Macron told viewers that France "will not give up our cartoons".
The service was attended by the teacher's family and some 400 guests.
The coffin was brought into the ceremony on the shoulders of a guard of honour and to the sound of the song "One" by the rock group U2.
On top of the casket was Mr Paty's Légion d'Honneur, France's highest honour. It was posthumously awarded to Mr Paty.
Mr Macron said Mr Paty had tried to teach his pupils how to become citizens.
"He was killed precisely because he incarnated the Republic", Mr Macron said. "He was killed because the Islamists want our future. They know that with quiet heroes like him, they will never have it."
Mr Paty had been the target of threats since he showed the cartoons of the Prophet Muhammad during a class on 6 October.
The history and geography teacher had advised Muslim students to look away if they thought they might be offended.
Depictions of the Prophet Muhammad can cause serious offence to Muslims because Islamic tradition explicitly forbids images of Muhammad and Allah (God).
What is the latest in the Paty case?
On Wednesday, prosecutors said Anzorov had paid two teenage students around €300 (£270; $355) to identify Mr Paty.
The killer told the students he wanted to "film the teacher [and] make him apologise for the cartoon of the Prophet [Muhammad]", anti-terrorism prosecutor Jean-François Ricard said at a press conference.
The students, aged 14 and 15, are alleged to have described Mr Paty, 47, to Anzorov and stayed with him for more than two hours outside the school until the teacher appeared, Mr Ricard said.
The pair, who cannot be named for legal reasons, are two of seven people the French authorities are seeking to prosecute over the brutal attack.
The prosecutor also said there was a "direct causal link" between the killing and an online hate campaign orchestrated against Mr Paty.
The campaign was allegedly launched by the father of one of his pupils. The man, 48, who has been named in French media only as Brahim C, is accused of issuing a "fatwa" against the teacher.
On Wednesday, Mr Ricard confirmed reports that Brahim C, who is also facing prosecution, had exchanged a number of text messages with Mr Paty's killer prior to the attack.
He also posted videos denouncing Mr Paty after he showed the cartoons in two lessons about free speech earlier this month.
But Mr Ricard said the father's anger and statements in the videos were based on "inaccurate facts" because his daughter had not been in the relevant lessons.
Mr Paty's killer, Anzorov, was born in Moscow and his family is from Russia's Muslim-majority Chechnya region in the North Caucasus. He had lived in France since 2008.