The attack took place when the teacher was alone in the classroom in Aubervilliers, French media said.
The attacker was reportedly wielding a box cutter and scissors and is still on the run.
France remains on high alert after the terrorist attacks in Paris on 13 November that left 130 people dead.
Fled on foot
Police sources said the teacher was stabbed in the side and throat at about 07:30 (06:30 GMT) as he was preparing for class in the Jean-Perrin d`Aubervilliers school.
The attacker reportedly arrived wearing a balaclava and gloves but was unarmed and used weapons he found in the classroom.
The man fled on foot after the attack and is still on the run. A search team has been deployed.
The anti-terrorism branch of the Paris prosecutor`s office has opened an investigation for attempted murder in relation to a terrorist act.
The Islamic State`s French-language magazine Dar-al-Islam recently urged followers to kill teachers in France, describing them as "enemies of Allah" for teaching secularism, Agence France-Presse news agency reports.
Security has been strengthened at schools since the Paris attacks.
Last week, Education Minister Najat Vallaud-Belkacem said the terrorist threat was "real and permanent", adding: "All public places must be protected, particularly schools."
Aubervilliers is in the Seine-Saint-Denis department of the Ile-de-France region.
In the 2010 census, Aubervilliers had a population of 76,000, including a large number of immigrants, mostly from North African Maghreb countries.
France teacher stabbed in class by man citing Islamic State
14 December 2015
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A teacher has been attacked in a classroom in a suburb of the French capital, Paris, by a man citing the so-called Islamic State group.
