Significa que el colegio/escuela es para niños con necesidades especiales, donde se practica la "educación diferencial" (niños con problemas de aprendizaje o algún tipo de discapacidad intelectual o física).

Special Education Schools
Special education is the individually planned and systematically monitored arrangement of teaching procedures, adapted equipment and materials, accessible settings, and other interventions designed to help learners with special needs achieve a higher level of personal self-sufficiency and success in school and community than would be available if the student were only given access to a typical classroom education.Students with special needs, such as learning differences, mental health issues, specific disabilities (physical or developmental), and giftedness are those whose needs are addressed within the classroom setting.

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Note added at 18 hrs (2011-03-02 00:29:07 GMT)
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Hilda, after reading your note I think my suggested "special education" fits well, even though the students are not exactly what we know as "special need children." I agree with you that the school is likely to provide education for troubled youths.