Prince Edward Island is changing how much university education is required for substitute teachers.

Teachers now need at least three years of post-secondary education, up from just one year, Nancy Desrosiers, registrar for certification with the Education Department, said Wednesday.

"There was a concern around the maturity level of a student who maybe has gone to university for one year and then goes back to substitute in a high school," she said.

"There was also concern around the academic background of young people that would be teaching our students. Another reason was that the P.E.I. standard was significantly lower than in other provinces."

Desrosiers said some other provinces require a teacher's certificate for all substitute teachers.

There are close to 600 substitute teachers on the Island, she said, and about one-third are not certified.

Certified teachers have an under-graduate degree and a Bachelor of Education, and they must be called first to substitute.

The Certification and Standards Board made the changes after receiving complaints that the some substitute teachers weren't much older than the students.

Desroisers doesn't expect the change to result in fewer substitutes. Substitute teachers with less than three years university experience can still teach if a school formally asks for that person, she said.

That might happen more regularly in rural P.E.I., where it's more difficult to find substitute teachers.

The changes will come into effect in September.