Avonbourne Trust has four academies; Avonwood Primary, Avonbourne College, Harewood College and Avonbourne Sixth Form.
George Duke-Cohan, 19, caused a massive uproar earlier this year after communicating a series of bomb threats against 1,700 schools, colleges and universities across the United Kingdom.
Judge Richard Foster said to Duke-Cohan: "You knew exactly what you were doing and why you were doing it, and you knew full well the havoc that would follow".
He began playing the game Minecraft and got validation from the people he met online.
His first bomb hoax email was prompted by a disagreement with the owners of VeltPvP, a US-based server that allows users to play the game Minecraft.
Duke-Cohan was arrested within days, but while under investigation in April he sent a further mass email to hundreds of schools in the United Kingdom and the USA claiming that pipe bombs had been planted on the premises.More news: Fatal brain-eating amoeba may have come from woman's neti pot
Duke-Cohan's bomb threat against United Airlines included him making a phone-call to San Francisco authorities in which he took on "the persona of a anxious father and [claimed] his daughter contacted him from the flight to say it had been hijacked by gunmen, one of whom had a bomb", said the National Crime Agency in a previous statement.
His emails threatened that an explosive device would be detonated if payment was not made.
The court heard that one of the emails, sent to a special needs school, read: "This is a message to everyone". We've sent in a student with a bomb.
Duke-Cohan, from Watford, had admitted making bomb threats to thousands of schools, including a number in Kent.
"The point is that when you put the school on lockdown this student will set off the bomb, and will kill EVERY student in the room and maybe the rooms next to it", he said in an email, adding: "Natural selection is coming and we plan on being the ones to start it off".
Duke-Cohan was arrested for a second time and released on pre-charge bail with conditions that he did not use electronic devices.More news: Epic Games’ store is now open, promises a free title every fortnight
Prosecutor Rebecca Austin said it was "clear" that Duke-Cohan used the influence of the Columbine attack of 1999 to add "authenticity".
Detectives found that Duke-Cohan had made the calls to San Francisco Airport and their police force while he was on pre-charge bail for the two previous offences.
In an operation supported by Hertfordshire Police, Duke-Cohan was arrested by NCA officers for the third time at his home in Watford on August 31.
Thousands of pupils from 457 schools who received similar emails were affected causing anxiety and upset, Luton Crown Court was told.
"You accept responsibility for the hoaxes and claim that you are a psychopath with a history of killing small animals", said the judge as he prepared to hand down sentence.
Judge Foster said that, for the purposes of sentencing, he accepted Duke-Cohan had autism spectrum disorder.More news: Gov. Cooper orders flags fly half-staff in remembrance of George HW Bush
Anya Lewis, mitigating for Duke-Cohan, described him as "vulnerable" and "remorseful".
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