For many teachers overseas, the first and most important lesson is survival
Safia Ama Jan paid a high price for her vocation. The teacher was gunned down in hail of bullets fired by two men riding past on motorcycles as she left for work.
Her crime? To teach girls in Afghanistan. Safia Ama Jan, in her mid-fifties, risked her life to run an underground school at her Kandahar home during the terrifying Taliban regime.
After the regime's fall in 2001, she opened schools to teach hundeds of girls and became the director of women's affairs for Kandahar province.
Under the Taliban, education was neglected and girls were banished from school altogether after the age of eight. Once the regime had gone, Afghan children, boys and girls, rushed back to classes.
More than 500 British schools helped raise pound;250,000 in a campaign run by The TES and Unicef to provide new buildings and equipment.
But five years on, schools and their advocates, especially those who were outspoken in their criticism of the old regime, are targets once again.
Safia Ama Jan's assassination on September 25, almost certainly by the resurgent Taliban, was immediately condemned by the director-general of Unesco, Koichiro Matsuura.
He said: "Education is one of the pillars of development, prosperity and peace. It is a human right. Safia Ama Jan's violent death serves as a grim reminder that those working to defend human rights are often working on the front line, with their lives constantly under threat."
Unesco is undertaking a major study of violence against teachers around the world and will look at measures to protect them, he said.
Amnesty International is also concerned that teachers are getting rough treatment, especially in Ethiopia where the 500,000 members of the country's teaching union face intimidation.
Washihun Melese and Anteneh Getnet, both members of the Ethiopian Teachers Association (Eta), were arrested in the capital, Addis Ababa, on September 23. Mr Melese teaches at Addis Ketema high in Addis Ababa and is an elected member of Eta's national executive committee.
Anteneh Getnet, also a teacher and Eta activist, was snatched from the union's office by three plainclothes policemen. He had been arrested and beaten before, in May. Both were released on bail last week. They have not been charged.
Hundreds of teachers have been arrested or arbitrarily sacked for failing to show support for the ruling Ethiopian People's Revolutionary Democratic Front.
Eta's criticism of government education policy has made targets of its officials, said Amnesty International.
The officials have managed to see off numerous government attempts to shut it down, including the setting up of a rival union with the same name. Mr Melese and Mr Getnet were held incommunicado and were at risk of torture, ill-treatment, or disappearance, the charity said.
Their arrests may be connected to a complaint lodged by Eta with the International Labour Organisation, citing government interference with Eta activities and intimidation of members. Hundreds of teachers have been arrested.
Kate Allen, the Amnesty's UK director, said: "To arrest these two men because of their involvement with non-violent trade union activities and then to deny them legal representation is absolutely unacceptable."
Another teacher and Eta official, Kassahun Kebede, is on trial on charges including an "outrage against the constitution", for which he could face the death penalty.
Trade union activity and opposition to corruption has made teaching a hazardous profession in many countries
Union activists have been shot at and arrested during a long-standing protest against the governor of Oaxaca.
German Mendoza Nube was detained last month and charged with illegal possession of a firearm, which he denies. Amnesty International has doubts about the legal proceedings.
Police beat the family of Abraham Martinez Alvarez, former rector of Oaxaca university, in an attempt to find him after he was publicly identified with the protests.
Claudia Rivas's life is in danger after denouncing alleged corruption in the ministry of education. An attempt has been made to kill her and her seven children are thought to be at risk.
Samuel Morales had been in custody for a year when a paramilitary group backed by security forces threatened to kill him and his family. He was charged with engaging in guerrilla activity, allegations believed to be spurious.
Rong Chhun, president of the Independent Teachers' Association, was arrested and detained for criticising a border treaty with Vietnam.
Scores of teachers were executed by Maoist rebels in 2002. They were targeted for singing the national anthem and for teaching Sanskrit.
Two unnamed teachers arrested in 2004 following demonstrations were sentenced to 1,500 lashes, to be carried out in front of their families, students and colleagues.