Lucas Backhouse, 18, began skipping lessons at Cardinal Newman Sixth Form College in Preston because he was struggling to cope with extra sessions designed to help him catch up.
Assistant Coroner Sara Sutherland was told the popular explorer scout from Garstang had mentioned to his brother he had once contemplated suicide.
But teachers and friends all said he had shown no signs of taking his life despite the difficulties he had been having at college.
And a therapist, who had worked with rugby-loving Lucas over concerns he may have ADHD, told the hearing at Preston: "He was adamant it was just a one-off - just what he had felt at that time.
"I didn't have any feeling that he could be a risk to himself."
Lucas was found dead by his father at the family home in Richardson Avenue, Garstang one evening in October 2021.
He had spent the previous night with his girlfriend and she had reported he had "seemed happier that he had been in a while" when she walked with him to the bus stop the following morning.
Lucas had been studying maths at Newman College together with other subjects. The inquest heard he needed a good A-level grade in maths because he wanted to join the Royal Air Force.
But the work proved a problem for him - especially when lessons were held online during the pandemic - and he started to slip behind, resulting in him having to resit the first year of the course.
When he began Year 12 for a third time, teachers decided to "double block" him with Year 13 work, meaning he would have twice the number of maths lessons, replacing business studies which he had already passed.
Newman Principal Nick Burnham told the hearing that it had been a "judgement call" by the staff who felt it would be beneficial. But Lucas's motivation declined and he appeared to completely disassociate himself from college.
They didn't think he wanted to be at Newman at that stage. Yet he was not considered a risk to himself.
There were "absolutely no concerns" about his mental health. "It was a real shock. He wasn't regarded as a vulnerable student," he said.
"To be honest, with hindsight, I don't think Lucas should have been doing A-level maths because he was clearly struggling.
"The staff were desperately sorry to hear of Lucas's death. Those staff, and the college, have looked at themselves to see what we can do better in the future."
Reaching a conclusion of "suicide," Assistant Coroner Sutherland said there were "a number of outstanding questions" that Lucas's family still had and his death had clearly taken everyone by surprise.
She said the statements of his teachers showed they were all working with him in the hope of him returning to engaging with his maths course.
She added: “What is very clear to me is that there is no doubt Lucas was an incredibly loved son and will be greatly missed by his family.”
Lucas was said to have had “a very high intellect” but had not been engaging with college teachers. His therapist added: “He was super bright.”
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