Stephanie Hudson enrolled her son at Merrillville's Pierce Middle School as an eighth-grader in August while he was living with Hudson's aunt in that town.

Hudson, of Gary, said she is frequently out of town because of her job and didn't want to take the chance of leaving him at home by himself. So she enrolled the boy in a school district other than the one in which she resides.

Merrillville school officials eventually found out, and Hudson's case went before school hearing officer Dan Friel, who ruled in Hudson's favor.

While Hudson's situation was resolved to her benefit, more often than not Merrillville school officials say they find that dozens of students are enrolled in their district illegally. School districts throughout the region have struggled with the extra expense of educating children who don't actually live within the districts they attend.

Former state Sen. Rose Ann Antich, now Merrillville clerk-treasurer, said she has seen people drive to a bus stop in Merrillville and drop their children off and pick them up again in the afternoon.

Antich said she has gone so far as to follow the driver, who has returned to Gary. Antich reported the information to Merrillville school officials.

Merrillville Superintendent Tony Lux said the district investigates about 100 residency cases each year.

"What people don't understand is that you don't just submit an address, even if it's with a relative," he said. "The student actually has to live there, and there is a variety of residential information that has to be submitted." Lux said it hurts the district financially, and it creates crowded classrooms.

Lux said the district is growing by 200 to 250 students each year, and based on the state's funding formula, Merrillville's per pupil cost is about $4,822 for 2007, up $51 from the previous year.

While Merrillville never has accepted tuition payments for students living outside the district, both Valparaiso Community Schools and the School City of Hobart do.

Valparaiso Assistant Superintendent John Hutton said about 100 out-of-district students pay tuition, and the policy has been in place for years.

In Valparaiso, the cost is about $2,400 for elementary school students, $2,600 for middle school students and $2,700 for high schoolers.

Before students are accepted, Valparaiso will assess their grades, attitude and ability to succeed.

Hutton said the district also checks to make sure the addition does not overcrowd classrooms. Hutton said he personally investigates reports of students who are attending the school based on false residency.

Hobart Assistant Superintendent Rich Edwards said residency issues are a growing problem.

"I am devoting more and more time to verifying residency," he said, adding that he follows up with phone calls, home visits and requests for further verification.

"I am actively investigating about 30 students whose residency is questionable," Edwards said.