The teachers in San Jose Unified have agreed to extend the school day without extra pay permanently, starting next year.

That gesture on students’ behalf would be noteworthy any time. But coming in a catastrophic budget year, when teachers are being asked to enlarge classes and take pay cuts, it is quite remarkable.

I mentioned this development last week, in the middle of a column on furloughs. It bears repeating and further explaining, since skeptics have told me I must have missed something; unions don’t give up anything for free.

They’re partly right; the teachers made this concession amid tough bargaining. But while the agreement wasn’t selfless, it was nonetheless enlightened. And it shows that creative solutions are possible in hard times when unions and administrators negotiate in good faith.

All  teachers in the 31,000 student district will now work 1,400 minutes of contact time each week with students. For high school teachers, that will amount only to an extra 25 minutes each week. But for kindergarten teachers, that’s 200 extra minutes – 40 minutes per day – and 50 minutes per week for middle grades. The district will suggest uses for the time, but Superintendent Don Iglesias said that school sites will determine whether to create student advisories – one suggestion – or add time daily to core classes.

The extended day was one piece of an agreement in which the teachers union agreed to larger high school classes  and to five district-wide furlough days, which will amount to a 2½ percent pay cut for all employees.

The extended day won’t save the district any money, but it did help the teachers stave off even harsher concessions. Here’s why:

San Jose’s teachers contract is unusual. For years, it has committed 67 percent of general tuition money from the state to salaries and benefits (categorical funding and special appropriations, like federal stimulus aid, are excluded) . The agreement has helped build trust between the administration and teachers, since the deal is clear and transparent, void of hide-the-dollars suspicion of teachers in other districts.

During healthy years, when the cost of living increase is fully funded, teachers do well. But in fallow years, when the school funding is cut, teachers can take a direct hit in pay.

That would have happened already, except that the contract allows one year of reprieve. But this year was to be worse.

The extended day, in effect, serves as a “credit,” wiping out further pay and benefit cuts. In return, the district has agreed to accelerate the use of the district’s healthy reserve over the next three years.

Union negotiators proposed the extended day. By establishing a uniform day for all teachers, it put to rest resentments that some teachers were getting paid for working less time.

Other districts and unions may have different priorities and less amicable union-district relations. San Jose Unified’s deal is a tribute to the rapport that Iglesias, who retires this year, other administrators and union leaders have built. It’s invaluable in years like this.