THE sentencing of a 10-year-old boy who raped an eight-year-old has been delayed because a magistrate is not sure the child has the capacity to understand the court process.

The child, who can not be named for legal reasons, assaulted another boy in December.

He pleaded guilty to one count of sexual penetration of a child and one count of threatening to kill.

The offender's sentencing was delayed this morning after a psychologist raised capacity issues in a report to Perth Children's Court.

Magistrate Andree-Marie Horrigan said in light of the report and the boy's age she was not willing to deal with the matter without a further report on his fitness and capacity.

Defence lawyer Neville Barber told the court he thought the psychologist had misunderstood the criminal code when it came to capacity.

He said the findings were inconsistent with what the child told the psychologist.

"(The offender) was well aware of what he should not have done," he said.

"On my instructions he is well aware that he did what he should not have done."

After he was charged, the boy was released on bail and was allowed to return to his northern suburbs primary school.

It is understood he had to be constantly supervised while at school.

Outraged parents gathered outside the school on Monday to discuss their concerns for their children’s safety.

They said they were angry they had not been told about the attack, with some parents refusing to send their children to school because they believed the offender was not always being supervised.

The school posted two security guards at its gates yesterday and displayed an electronic sign that said “all students are safe”.

An Education Department spokeswoman said the student was being constantly supervised by two staff members and the school was doing everything reasonably possible to ensure the safety of all students.

She said the Education Act guaranteed the right of every child to an education, even if they faced criminal charges.

The eight-year-old victim does not go to the same school as the offender.

The case was adjourned until next month so a fitness to stand trial report could be prepared.

Ms Horrigan extended the boy's bail.