IF ARLENE ACKERMAN had ever been through a messy divorce, she would have learned to play the joint-custody game.

She would have known to dress the kids in runover shoes and threadbare coats just before their dad picked them up for the weekend. She would know that you never go to the courthouse in designer jeans to petition for more child support.

That's how you play the joint-custody game. Each parent hides assets and exaggerates liabilities while the kids play the part of flyspecked waifs.

That's how it's done in public-school financing, too. In a district that is neither a ward of the city nor the state, nobody accepts full responsibility.

"They are in a beggar's position," city Controller Alan Butkovitz told me yesterday. "They don't own their own house because they can't raise their own taxes."

Philadelphia mayors and Pennsylvania governors have always played the joint-custody game. Each sends a fat check every year and then tells the other parent that whatever this doesn't cover is on you.

But Michael Nutter took on a more activist role. He pledged to find up to $110 million in the city budget for the schools and was willing to put his money up before going to the state to ask for its help.

I asked him last week if he'd be willing to fight for more taxes for the schools. "Yes, if it comes to that," he said. "This is a leadership moment."

That it is. City Council would sooner take a sharp stick in its collective eye than lead a campaign to raise taxes for any reason.

So, I am feeling the mayor's pain this week. Superintendent Ackerman's deal with the state on Friday to save full-day kindergarten left him standing in the square with a blunt instrument in his hands.

She moved Title I federal money to augment the budget for full-day kindergarten, depleting funding in other categories she felt were less crucial.

I'm glad she did it. I can't be an advocate for a brinkmanship strategy. I understand why it's done. But I have never believed it needed to be.

Grownups should be able to understand the need to fund schools even if we're not facing apocalypse now. There is plenty left for the mayor to advocate for.

Key early-childhood programs are on the chopping block. A thousand teachers are facing layoffs, which would increase class size significantly. The state has cut the $100 million line item that supported the city's charter schools. Summer schools that played a huge part in raising graduation rates by 4 percent in the past two years face elimination next year.

The district is looking to save $26.5 million by eliminating school-bus services and postponing payment for free SEPTA TransPasses for indigent children. Art, music and athletic programs are in jeopardy.

With all of that hanging out there, do we really need to use the 14,000 kindergartners as bargaining chips?

"We can tie the eight years of improved test scores directly to full-day kindergarten and early-childhood programs," Ackerman told me yesterday. "Every study for years has shown that young people engaged in full-day kindergarten are better prepared.

"My office was flooded with calls and emails from parents. People stop me in the street. They needed to know now. What is a working parent supposed to do when their kids are home for half a day?

"This is a permanent fix. We don't have to worry about who is in the governor's office anymore.

"I just learned that I could this Friday. I wasn't trying to be the hero. But how would it look if I held it up for political reasons and then people found out that I could have done it weeks or months ago?"

Meanwhile, the mayor is building up enough steam under his collar to heat the schools for a semester.

But that's just between us. I wouldn't want that to get out while he's still trying to raise money for the schools.

Send email to smithel@phillynews.com or call 215-854-2512. For recent columns: www.philly.com/ElmerSmith