Boko Haram is singling out geography teachers in its campaign of terror against Western education in Nigeria, it has been revealed.

Teachers of the subject have emerged as an unlikely top target for the group because their lessons contradict its bizarre worldview on how the Earth was created.

Boko Haram believes that the Earth is flat rather than spherical, and that rainfall is caused not by evaporation, but by God’s divine will.

As such, geography teachers are ranked alongside Nigerian security chiefs and senior politicians as prime candidates for assassination.

The threats to geographers are outlined in an extensive new report by Human Rights Watch, which lays bare the devastating impact wreaked by Boko Haram on Nigeria's school system.

It says that a total of 600 school staff have been murdered by Boko Haram since 2009, and that 19,000 have quit their jobs due to threats and attacks.

The report is timed to coincide with this Thursday's two year anniversary of Boko Haram's kidnapping of more than 200 schoolgirls from the town of Chibok in Borno state in north-east Nigeria. They remain as hostages to this day.

The report says that in Borno, which is Boko Haram's main stronghold, schooling in 22 out of 27 local government areas has been closed down, depriving hundreds of thousands of children of the right to learn.

“In its brutal crusade against Western-style education, Boko Haram is robbing an entire generation of children in northeast Nigeria of their education,” said Mausi Segun, Human Rights Watch’s Nigeria researcher.

The 86-page report, based on interviews with more than 200 teachers, students, parents and school officials, documents numerous attacks on schools by Boko Haram gunmen, some of which ended in abductions and some of which ended in massacres.

It notes: “Boko Haram insurgents have shown particular distaste for certain subjects like geography and science... Teachers of these subjects are targeted."

One such attack took place at the Mafoni Government Day Secondary School in Borno's regional capital, Maiduguri in September, 2012, when gunmen burst in and "set their sights" on the geography teacher, Malam Anjili Mala.

One witness, whose name was withheld, told Human Rights Watch: "I dived for protection, but the gunmen simply rained six bullets into the teacher and calmly walked away. No one else was touched."

The principles of geography and social science contradict of the eccentric teachings of Boko Haram's late founder, Mohammed Yusuf, who was killed by Nigerian police in 2009.

In an interview with the BBC in which he claimed that Western education was contrary to Islam's values, he said: "We believe that rain is a creation of God rather than an evaporation caused by the sun that condenses and becomes rain.”

He also said he rejected Darwinism and the idea that the “world was a sphere”, which he claimed ran “contrary to the teachings of Allah”.