title: Performance of mentally retarded children on pre-arithmetic tasks.
mesh_terms: D000293:Adolescent; D001244:Association; D002648:Child; D002675:Child, Preschool; D003210:Concept Formation; D004192:Discrimination, Psychological; D004495:Education of Persons with Intellectual Disabilities; D006801:Humans; D007804:Language Development; D008433:Mathematics; D011340:Problem Solving; D013663:Teaching; D014705:Verbal Behavior