What would happen if Bonnie Nagel stopped rewarding her attentive fourth-graders with tokens redeemable for bendy straws and bouncy balls? If correct answers in math didn't rate them Now and Laters? If Mrs. Nagel didn't bake them brownies for earning good-behavior points in art and gym?

"It would be like a dungeon," said Ricky Frank, 9.

"Then I'm not coming to school," said Kwabena Nimarko, 10.

"That's, like, what we live for," said Katherine Driessen, 9.

Enter just about any elementary or middle school, and you'll find that for doing well, students constantly are rewarded with stuff: McDonald's fries for good grades, pencils if they show up for standardized tests, a chance for a restaurant lunch if they do a good deed.

These incentives--descendants of the good old gold star--have proliferated in the face of highly critical research. In a slew of articles, academics say teachers' reliance on extrinsic motivators--in which the reason for doing something is a reward other than the activity itself--is an insidious cop-out that turns classrooms into game shows and forever kills children's inner enthusiasm to learn or behave.

"I've read those articles," said Nagel, a teacher at Swansfield Elementary in Columbia who, like many other teachers, dismisses them as poppycock. "There are those children who are on their best behavior all the time, but there are children who need that extra incentive. It's hard to pay attention--we're 9."

Despite what critics fear, teachers such as Nagel hope that intrinsic motivation grows from the extrinsic. That the boy who rushes through 30 books to win a pizza finds an author he likes and begins reading for fun. That, like Pavlov's dogs, children will be enthusiastic about the activity even after the recompense disappears.

Rewarding children for their actions is, of course, nothing new and not unique to teachers. Parents have forever doled out Raisinets for toilet training, sports cars for straight A's. Extrinsic motivation was hugely fashionable in schools three decades ago, when B.F. Skinner's rats showed the world how well behavior could be learned. But it became seen as an inappropriate manipulation of children and mostly disappeared in the classroom--until lately.

Now educational incentives are commonplace and corporations are joining in. Pizza Hut's Book It! program--where students win a small pizza for every month they read a certain number of books--has reached more than 895,000 classrooms, and in a program called Can-Do, students with good grades and behavior get photo IDs good for McDonald's fries and other treats.

Educators rely on such incentives at a time when studies show it is harder than ever to motivate students. There is no fix on why teachers are grasping at ways to engage children, but commonly cited culprits include busy parents who don't demand much or don't pay attention, more family and societal problems, rife consumerism and scanty Nintendo-era attention spans. "I think the world has changed," said Marion Miller, principal of Running Brook Elementary School in Columbia, "and we have adapted to it."

At the same time, aspiring teachers don't get many lessons on motivation in school. Said Judith Meece, an education professor at the University of North Carolina, "What happens is, the teachers go out, they don't have any strategies, they just rely on their preconceptions of what works."

And in the here and now--which is often all a harried teacher can worry about--extrinsic motivation works. A smiley-face eraser is striven for with as much dedication and accepted with as much joy as a handpicked trinket from the FAO Schwarz catalogue.

Yet the simplicity of such reward systems fuels skepticism. "I think there's a persistent interest in education and a tendency for us as a society to jump at easy solutions," said Mark Lepper, a Stanford University psychology professor and well-known critic of extrinsic motivation.

When they studied children given rewards for doing activities, Lepper and his peers found that the youngsters take the easy way out. They don't concentrate well, paying attention more to the prize than to the task. They perform worse and recall less.

And there's the long-term effect: "If you've got kids at a young age who are eager to learn and then start rewarding them, creating these structures, it may get them to do things in the short term, but it kills the love of the learning," said Edward L. Deci, a University of Rochester psychology professor.

Or another extrinsic motivator takes its place. When Nick Baker, 15, was in middle school, his grades jumped a full letter all because (he insists) of the Jolly Ranchers his teachers let him eat in class. Now that he's a sophomore at River Hill High School in Clarksville, "they just tell you, 'Do your work, or I'll fail you.' " And he does, because even though he misses the candy, "high school is more important than middle school for my future."

Indeed, by high school, the long-term rewards of achievement and penalties for slacking are more imminently clear.

Still, Meece believes, "you can get as much from kids through praise and a smile." Thus she is puzzled that at Swansfield, praise has become another currency. Every time a teacher compliments the children--for lining up nicely, cleaning up quickly--the compliment is written on a slip of paper titled "You Earned It." A copy goes to Principal Earl Slacum, who draws one each week for a pizza party.

In other words: The compliment isn't reward enough.

Slacum, a 32-year educator who remembers the gold stars on his boyhood papers, defends the technique. "Younger children especially, you have to have them see the reward. . . . If they're not endorsed, they don't see that big picture."

When he visited Nagel's classroom "store," where math students cash in their reward "money," he said children pointed out: "You get paid every day to come to work, don't you? Why shouldn't we?"

Realizing they can't abolish rewards, academics offer situations in which they might be acceptable: With dull, routine tasks. With students who have little control over their behavior. When incentives have to do with education, such as special time with the teacher. And when the rewards are doled out unexpectedly.

Nagel agrees with that part. "I think if you're telling them it's for this specific thing, it's bribing," she said. "But here, they never know it's going to happen."

That's not entirely true.

Nagel is the perfect teacherly combination of sweet yet firm that makes children pay attention. She creates fun activities, and to some degree the students work at their own pace. But they all say their minds are finely tuned to popcorn.

Nagel keeps two measuring cups of kernels at the front of the room. When the children appear hushed and industrious, she says, "Boys and girls, I'm going to move a scoop over because you're all on task." She pours popcorn kernels from one cup into the other; when the second cup is filled, the corn is popped for a party.

Students know when they're slipping toward popcorn removal. But usually--before Nagel says, "I do not want to subtract popcorn"--they calm down, knowing the stakes.

Although Katherine, the 9-year-old, loves the popcorn ("It really helps you be good if there's something to earn"), she has thought more about the idea of losing all the incentives, and she has a new answer.

"It would be a change of pace," she said, "because then we might be good for the sake of being good. The rewards kind of tell us we're not being the best class in the world on our own."

Next to her, Kwabena groaned.

CAPTION: Bonnie Nagel, a fourth-grade teacher at Swansfield Elementary School in Columbia, hands out a reward for good behavior--a practice not all educators endorse.