They sought the help of full-time math teachers, consulted books and online sources and, whenever possible, taught one another.

FORBES: A Curiosity-Driven Education

The latest public sector employment figures showed 54, 600 full-time equivalent teachers between April and June this year - down 2, 200 on the same period last year, when the figures stood at 56, 800.

BBC: Teacher numbers in Scotland at eight-year low

The latest figures showed there were 54, 600 full-time equivalent teachers between April and June last year in Scotland - an eight-year low.

BBC: Review of McCrone teaching deal announced

The statistics show there were 899, 000 full-time equivalent staff in England's schools - teachers, teaching assistants and other school staff - up 23, 200 on the previous year.

BBC: Hundreds of school leaders paid in excess of ?100k