As a result of some speeches made and some laws passed somewhere far away where the president lives, all the kids in Debra Thuma's second-grade class at the Tooker Avenue Elementary School were down on the floor, bicycle-pedaling their legs in the air on Friday morning.

Except for a few of the girls. They stood near their desks.

''It's the dresses,'' explained Mrs. Thuma. ''At this age, a lot of the girls wear dresses. Isn't that lovely? But they don't necessarily like putting their legs up in the air.''

Exercise in most public schools used to happen only during two gym periods a week. But to meet a federal mandate calling for more supervised physical activity, many schools around the country have begun daily fitness workouts like the one in Mrs. Thuma's class here.

Some are improvised, and others, like Mrs. Thuma's, are conducted with the help of videotaped programs that take the kids through a 5- or 10-minute session of jumping jacks, running in place, situps, push-ups and the above-mentioned bicycle pedaling, which some of the girls, according to Mrs. Thuma, really hate.

It is a condition of childhood that grown-ups decide what is good for you, however; and following a series of studies chronicling the increasing rates of obesity and diabetes in children, the deciders in the federal government ordered more activity.

The order was embodied in Section 204 of Public Law 108-265, the Child Nutrition and W.I.C. Reauthorization Act of 2004, which requires that by the end of the 2006-7 academic year -- by now, in other words -- schools provide daily ''physical activity and other school-based activities designed to promote student wellness.''

At Tooker, this means a prodigious amount of foot-stamping, hand-clapping, jack-jumping and other types of otherwise forbidden behavior taking place right in the middle of the morning, between lessons in cursive, double-digit addition and the science of magnets.

''The idea is that it's not enough to have an athletic program or gym class twice a week,'' said Lou Howard Jr., the physical education director for West Babylon schools. ''Kids need to be physically active during the day, every day. This is a program that regular teachers can do. You don't need to be in phys-ed class.''

To meet the federal deadline, three weeks ago administrators at Tooker Avenue Elementary introduced a seven-minute exercise tape produced (and provided free of charge) by a Long Island company, Kid Fitness.

The company, which produces a children's exercise show of the same name for public television, hopes to have its fitness tape used in elementary schools throughout the country. As part of a promotional effort, it donated 9,800 copies to the New York City school system in February -- enough for all classes from kindergarten through the second grade.

On Friday, the star of the tape, Kid Fitness himself, a very fit 26-year-old actor named Casey Unterman, visited the elementary school here.

After asking Mrs. Thuma's 23 students if they were ready to have some fun, Mr. Unterman, dressed in the superhero costume of his character, provided a crisp, precise demonstration of all the exercises that the children, facing him, performed in their own younger, wilder versions.

Mrs. Thuma said that in her 15 years of teaching second graders, she noticed that ''most kids are pretty fit at this age'' but become less active later on. ''By fifth grade,'' she said, ''you start to see the overweight kids.''

Stephen J. Virgilio, chairman of the health and physical education department at Adelphi University, and a consultant to the Kid Fitness company, said that between the fifth and 10th grades, many children become physically inactive. ''Partly it's because of video-game and television habits,'' he said, ''and partly it's the influence of too much organized sports -- when the kids drop out of organized sports, they don't know how to play. They just stop.''

That is why promoting nonsports exercise for children at a young age, as the federal law requires, is ''such a good idea,'' he said.

When the kids, sweating and flushed, were done with their exercises for the morning, Mr. Unterman asked if they did not love feeling ''fit and healthy.''

They did, they said.

''I like having it first thing in the morning,'' said Jessica Marmaroff, 7, speaking later to a reporter who asked about the regimen, ''because then, like, you don't have to do a lot of work.''

And what about the issue of the dresses?

Emily Tartaglia, 7, explained that this was not necessarily the deal breaker that some might have one believe.

''All you have to do is hold your skirt like this,'' she said, gathering the folds on either side of her skirt and in two no-nonsense fists. ''You just have to not forget.''

Photo: Casey Unterman, a k a Kid Fitness, leads second graders through their morning exercises at the Tooker Avenue Elementary School. (Photo by Ed Betz for The New York Times)