Manchester United star Marcus Rashford was one of dozens of celebrities who tweeted messages on Friday, 22 May, in support of the victims of the attack in the foyer of an Ariana Grande concert three years ago.
The mother of one of the 22 victims, Martyn Hett, has also given a stark warning that jihadist terrorism remains a threat.
Figen Murray, who has visited dozens of schools, colleges and universities in the last three years, said teachers "need to be very observant" to the signs of radicalisation.
She told PA News: "If somebody has been recruited or radicalised, there are tell-tale signs in their language and behaviour. A lot of teachers will hopefully be well versed in that."
Salman Abedi and his brother Hashem were both radicalised in the run-up to the 2017 attack.
In March this year, Hashem - who was extradited from Libya - was found guilty of the 22 murders and was about to be sentenced when the coronavirus outbreak hit Britain. He faces a mandatory life sentence.
During his trial at the Old Bailey it was never suggested the Abedi brothers had deliberately chosen to conduct their attack on the same date - 22 May - as Lee Rigby’s killers Michael Adebolajo and Michael Adebowale.
Because of the coronavirus outbreak and the lockdown, families of the Manchester attack are forbidden from grieving together but the Dean of Manchester, Rogers Govender, is holding online services on Friday, livestreamed on Manchester Cathedral’s Facebook page.
Stickers of a bee - which became the defiant symbol of Manchester after the attack - have also been posted at two metre intervals on the floor around a memorial to the victims at Manchester Victoria Station.