pl. remedial classes are necessary during the education of young people with special needs

Remedial classes are necessary for students who don't understand a subject properly. Teachers should keep in mind that not all students have the same

http://en.wikipedia.org/wiki/Remedial_education

Postsecondary remedial education (also known as postsecondary remediation, developmental education, basic skills education, compensatory education, or preparatory education) is a large and growing segment of higher education in the United States. It is composed primarily of sequences of increasingly advanced courses designed to bring underprepared students to the level of skill competency expected of new college freshmen. Estimates suggest that as many as 41% of all new college freshmen enroll in remedial coursework during their postsecondary pursuits.

http://en.wikipedia.org/wiki/No_Child_Left_Behind_Act

http://www.learnersdictionary.com/search/remedial
involving students who need special help to improve in a particular subject
▪ Thirty percent of the new students need remedial classes/courses in math. ▪ remedial education ▪ He's taking a course in remedial reading. ▪ (US) a remedial student [=a student who is taking a remedial class]