First, there's the mystery of the disappearing kids.
Ann Arbor's enrollment dropped by about 200 students this year.
That's a surprise, School Board Treasurer Glenn Nelson says, because enrollment was basically stable last year.
Administrators do know where about 50 of those kids went: the Washtenaw Intermediate School District, which offers specialized programming.
But the other 150 students?
"I don't know," says Nelson. "And that's something I wish we knew more about."
Did they move out of state? Choose another district? Decide that this was the year they opt for private school?
Ironically, the district's previous cuts mean it doesn't have the staff to dig deeper into these losses, says Nelson.
"We have so constrained our central office staff, that we don't have much capacity (to look into this) he says.
Nelson says they'll get more answers as the state publishes its district-by-district enrollment numbers.
Meanwhile, district spokeswoman Liz Margolis says they're stepping up efforts to get more kids to choose AAPS, like virtual high school programs and a new K-8 curriculum focusing on STEAM (Science, Technology, Engineering, Arts and Math) at Northside Elementary school.
"This is a different perspective for this district," says Margolis via email.
"In the past, it has been cut, cut, cut. Now, while we have to make some cuts, we are anticipating these new programs will increase enrollment."
Teachers agreed to big cuts last year, but that one-year deal is up
But the big budget issues are deeper than 200 kids taking off for other pastures.
Sure, fewer students means less money for the district.
But the looming $10 million hole for next year is due largely to a mounting stack of bills to pay.
"Almost a third of it is restoration of teacher compensation cuts," says Nelson.
"We negotiated a one-year concession with them last year, and now that comes back into the budget."
Add onto that the rising contributions the district has to make into state pension and health care funds, he says.
Nelson says some of the district's newer teachers will also pull in bigger paychecks as they move the up the ladder of experience and training.
Counting on more kids to come next year, despite this year's unexplained drop
The district will figure out how to close that $10 million hole throughout public meetings over the next couple of months.
But Nelson says one thing they're not worried about is enrollment.
"We're not projecting another enrollment drop (next year). In fact, we're anticipating an increase."
Whether that's a good idea, given that this year's drop in students was such a surprise, is an open question.