HONOLULU -- Gov. Linda Lingle's plan to restore school classroom days may not provide enough cash to eliminate all 27 furlough days she wants, Hawaii Schools Superintendent Pat Hamamoto said.

Taking $50 million from the rainy day fund will cover basic school salaries, but Hamamoto said she might need more to cover expenses of opening schools. The superintendent also said that because many of the waiver days have already been used, it will not be possible to simply replace them with instructional days in the last six months of the school year.

Hamamoto will have to negotiate any change to the school calendar with the teachers union and the new deal and the Legislature and the governor must approve finances.

Lingle announced the plan on Sunday.

The governor wants teachers to use 15 non-classroom days to restore teaching lost on furlough Fridays.

Many teachers use Wednesday afternoons for administrative work. Instead, they would teach, and the governor wants to tap the Emergency Budget Reserve, the so-called rainy day fund to pay for 12 days.

The plan would allow furlough Fridays would continue through December, but get students back in class through June 2011.

When a special session would be held to pass a bill to stop the furloughs will depends upon how quickly a collective agreement is formed by all parties, especially with the unions.

However, with the school year nearly half over, that may be a challenge.

Holomua Elementary School in Ewa has a multi-track schedule. It is a good example of the complexities of adding education days. Like most schools, the waiver days are already gone, used for early-year teacher training.

"Most schools have already used waiver days. So how are we then going to change those?" sixth-grade teacher Will Kane said.

Third-grade teacher Julie Ramos said she and her teaching partner are happy to rearrange things, again.

"For other teachers it might not be that easy to plan and re-plan and re-plan again," Ramos said.

Another challenge is that students and teachers on Ramos' and Kane's track have taken fewer furloughs than other students. Will they be able to make those up or not?

"By changing it now you are going to have inequalities in instructional times and we've adjusted the curriculum and we planned ahead, and now to change it again, it's difficult not only on the teachers, but on the students as well,"

Add to that to change the furloughs. At least three unions are involved in supporting schools. Two would have to reopen negotiations. The Legislature would have to change two laws, all in less than a month and a half.

"It's entirely possible that we can't get back all the days," Schools Superintendent Pat Hamamoto said.

"I think it's fair to ask the teachers to step up like all the other workers in the state. I am just concerned more about the details how it's going to affect the teachers," Kane said.

"The proposal is OK with me. I will do anything to get the students their instructional time back," Ramos said.