Hayden Shipley was stumped.

Though the first-grader thought he knew his teddy bear, Jacob, pretty well, an interview question by fourth-grader Logan Sheehy gave him some pause.

"His favorite food?" repeated Hayden, looking quizzically at Jacob, who minutes earlier had been wearing a karate uniform but was now just wearing socks. "He doesn't have a favorite, but ... oh! Chicken. Me and him like chicken."

At McKee Elementary School in the West Allegheny School District, it was the day of the Teddy Bear Sleepover -- an activity first-grade teacher Debra Wolf has spun into a weeklong unit incorporating nearly every academic activity imaginable.

Her students draw bears. They count bears. They add and subtract bears. They make teddy bear puppets. They read stories about other bears. They answer interview questions about bears. They learn about the history of the teddy bear. They graph types of bears, and they input those graphs into a computer program.

But the hallmark activity is the sleepover. As they left school Wednesday afternoon, the students put their bears to bed, wrapping them inside blankets and pillowcases, reading them stories and brushing their teeth.

When they came in to the Oakdale school on Thursday morning, the bears had run amok. One had been caught with his paw in the candy jar and another had scrambled the student identification tags. There was a bear surrounded by scissors, crayons and scribbled paper, and there was a pair of headphone-clad bears playing on the computers.

The students had to write "essays" about what their bears had done overnight -- and what consequences they might face for their behavior.

It's the writing assignment that most energizes the students, said Mrs. Wolf, because it pushes many of them beyond their comfort levels.

"Right now, they're at the point where they can all write two or three sentences with capitalization and punctuation, but they can't think of what they want to say," she said. "This just gives them incentives -- it's about getting the creative juices flowing."

The sentiments expressed in the essays ranged from "my bear wasn't too bad" and "I love him anyway" to "my bear is grounded" and "my bear has detention."

Given the many moving parts that constitute the mental development of 6- and 7-year-olds, the writing assignment is one that requires delicate timing, said Mrs. Wolf.

Any earlier in the year and the students wouldn't be able to write essays with more than one sentence. But if they were much older, they would start to question whether the bears really "came alive" to get into all that mischief on their own.

Mrs. Wolf started the teddy bear unit about nine years ago on a much more limited scale. As she's built onto it year after year, it's become a well-known and well-loved exercise at the school.

As the fourth-graders filed into the room on Wednesday to conduct the interviews, many were visibly excited by the sight of the teddy bears. "Ooooh, I remember doing this," exclaimed one fourth-grader.

In the interview portion, the fourth-graders got a chance not only to ask questions and write down the answers, but also to read a story to the first-graders and their bears.

First-grader Taylor Upperman confidently answered most of the questions on behalf of her bear, Fluffy, who was decked out in a "Glamour Girl" T-shirt and bunny slippers.

She was just a little unclear about Fluffy's birthday, though she guessed that she was 19 years old. "She's really old," said Taylor.

The first-graders like the unit so much, said Mrs. Wolf, that a week is hardly enough for them. And though the bear theme will continue into the next week, as the class transitions to learning about wild bears in a science unit, that's hardly a consolation for the students.

"They all want to do it, like, every night," said Mrs. Wolf. "I told them, 'You guys, your bears made a mess. They're going home.'"