摘要：The current study strives to clarify the mechanisms used by mentally retarded children in the counting process which involves the equivalence, ordering and transitivity relationships that determines the number acquisition. It’s a comparative study with 4 and 5 years old composed of two groups: one group are mentally retarded children (between 8 and 12 chronological years old and 4 and 5 years-old, developmental age, tested by Métode Dimensional Cambrodí) educated in a special school; and the other group are not mentally retarded children educated in a mainstream school.
