New teachers will have to work for five years in the same district before earning tenure, after Gov. John Lynch this week allowed the change to become law without his signature.

The new law increases the length of time it takes teachers to earn tenure from three years, which is the term used in many states, to five years.

It gives New Hampshire the longest teacher probationary period of any New England state. In Massachusetts it takes three years to earn tenure. In Vermont and Maine, it takes two years.

Supporters of the legislation argued that because of the financial and legal hurdles it takes to remove tenured teachers, school districts needed more time to determine whether new teachers are cut out for the profession.

The state’s largest teacher union, the National Education Association, opposed the change, saying it would do nothing to improve education and administrators already have the tools to remove tenured teachers for performance.

Stretching the time it takes to earn tenure means teachers will essentially be probationary employees for two extra years. They can be let go at any time during that period and the district doesn’t have to give a reason.

Nashua Superintendent Mark Conrad supported the change.

“Some teachers we’re sure about after the first year,” Conrad said. “Other teachers, at the end of three years, we may not really be certain about whether they’re going to have the expertise in teaching we expect in the district.”

Rhonda Wesolowski, head of the National Education Association-New Hampshire, said earlier this month that three years should be sufficient time for administrators to decide whether teachers will be able to succeed in the profession. The focus should be on strong support and mentoring for new teachers who are struggling, she said.

“This flies in the face of everything we’ve learned about keeping the best teachers in the classroom,” she said.

Wesolowski also raised concerns about changes in the bill that she thinks will give teachers fewer rights when they are let go, eliminating requirements to provide evidence that teachers were given written notice of their poor performance as well as a reasonable opportunity to improve.

Michael Brindley can be reached at 594-6426 or mbrindley@nashuatelegraph.com.