I read a statement of Ibn Taymiyyah, and some people say that it shows that the so called marks in schools come under the same ruling. The statement is:
“And everyone who judged between [any] two people, then he is [considered] a qaadi (judge) irrespective of whether he is a person of war, or one commissioned into [any position of] office, or appointed in the consideration [of the affairs] of enjoining good and forbidding evil, until even the one who judges between two children regarding [their] handwriting, then the Companions considered [all] such people to be hukkaam (rulers).”
I want to know what the attitude of this website is about that because some people declare that everybody who goes to school is a disbeliever because they say that they choose the disbelievers as rulers.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.

The statement of Shaykh Ibn Taymiyyah refers to the people who judge among people, like judges and the like; they are enjoined to observe justice in all matters, even if the case is as simple as judging which handwriting of students is better. This applies to the teachers responsible for evaluating students and determining their grades; they are enjoined to observe justice and give each student the grade that he actually deserves.

However, this does not mean declaring whoever studies at the hands of a non-Muslim teacher or goes to a school supervised or run by non-Muslims a disbeliever. The basic principle is that it is permissible for the Muslim to learn at the hands of a non-Muslim teacher regardless of his religious affiliation. It has been reported that some of the Companions' children learned how to write at the hands of the polytheists who were captured as prisoners of war in the Battle of Badr. The Prophet, sallallaahu ʻalayhi wa sallam, declared that if one prisoner teaches ten Muslims how to read and write, then this would serve as his ransom and he would be set free. Ibn ʻAbbaas said, “As for the prisoners of war in the Battle of Badr who were too poor to pay any ransom and knew how to write, the Prophet, sallallaahu ʻalayhi wa sallam, asked them to teach ten Muslim children to write in lieu of their ransom.” [Al-Haakim in Al-Mustadrak]

However, the permissibility in this regard is confined to the case in which learning at the hands of a non-Muslim teacher would not be a source of misguidance for the student, leading him astray. The students in such schools that are run by non-Muslims are not seeking to have the disbelievers as their rulers to rule or judge according to other than what Allaah has revealed. Managing the affairs of a given entity, the assessment of skills, and availing oneself of the experiences and useful lawful knowledge of others have nothing to do with ruling or judging according to other than what Allaah has revealed.

Allaah knows best.