Slippery snow is turning to slush. It is midwinter in Kanto, time for bundling up in fleecy sweaters and heavy coats. But at the two Hikari Yochien schools in Kawasaki, boys and girls are playing outdoors wearing nothing more than gym shorts.

"We don't force children to take off their clothes," says school founder Naohiro Yoshida. "Kids would catch a cold if they were forced. They watch the elder kids, and when they feel ready, they take off their shirts by themselves."

Pupils at Hikari Yochien take part in painting (above) and taiko drumming classes (below).

Hikari Yochien's "naked education," an extension of the traditional practice at Japanese kindergartens of having children wear short pants in winter, has been widely written about and reported on television, both in Japan and abroad.

While some may question the wisdom of the practice, which is designed to help strengthen the constitution and encourage physical activity, an NHK study that followed the health of Hikari children in the six years of elementary school concluded that they were sick on average less than seven days throughout their entire primary school years. These tough little kids had fewer colds, with quicker recovery time.

"The first question parents ask when they hear about our school is 'Why?' " says Soji Matsumoto, the founder's son-in-law. In this highly unusual two-generation family business, mother and daughter serve as school principals and Matsumoto is head administrator.

"I give them the research done by NHK. Years ago, they used a pedometer to measure how much 'naked' children walk compared to children at other schools. 'Naked' children were found to walk about 20 percent more, and because they used more energy, they would eat 20 percent more."

Tots wearing only gym shorts 12 months of the year start the day with an invigorating ritual of kanpu masatsu (a dry towel massage) and a quick jog around the school property, before free outdoor play.

"Children make it into a game, saying goshi, goshi, goshi [scrub, scrub, scrub] as they rub each other outside in the schoolyard," explains Rosalind Brown, who has taught English at Hikari for nearly 14 years.

For parents, the issue of "nakedness" starts out big, but becomes almost superfluous compared to Hikari's innovative methods for getting children to read kanji at a 12-year-old's level by the time they enter first grade. Then there are the other weekly offerings: English lessons, art classes with a professional artist, music lessons with gleaming taiko drums, calligraphy lessons and natural pursuits -- tending a vegetable garden, raising silkworms, digging for sweet potatoes.

"There was a professor Isao Ishii who wrote many books about kanji and how it helped develop children's minds," Yoshida explains. "Ishii said children remember kanji more easily than kana because the shapes are more complex, have specific meaning and are each individual."

It took Yoshida six months to persuade his wife, Kiyo, the principal at Dai-Ichi Hikari, the first of the two schools, to try his innovative approach: making an environment where kanji were introduced through flashcards and creative games.

"There are no exams, no scores, no forcing," he says.

Another of Yoshida's mentors, Shin'ichi Suzuki, who achieved worldwide fame for what is now referred to as the Suzuki violin method, made Yoshida think that if 3-year-olds could be taught the violin, they could surely learn kanji as well. Suzuki was a master of making learning fun, encouraging very small children with lessons calculated to make them smile and return eager for more.

The school offers drumming, rhythm and music reading to all of the children, and the option of private violin, piano and cello lessons after school hours.

Hikari Yochien's Dai-Ichi and Dai-Ni schools in Kawasaki were like most postwar kindergartens when they were founded in the 1950s, but by the early 1970s, Yoshida had discovered the teachings of human potential pioneer Glenn Doman and traveled with several of the Hikari staff to Pennsylvania to study his methods.

Doman believes that all children are geniuses from birth, meaning that they can learn vast amounts of material far more easily at young ages. Unless this early childhood intelligence is developed, however, by age 6 it begins to decrease. Doman's theory is controversial, and although it has found support in the U.S., kindergartens in Japan have been slow to embrace it. So Hikari keeps its doors open year-round to let prospective parents witness these whiz kids in action.

The first thing a parent might notice is that a kanji-learning environment is the backdrop to everything the children do at Hikari. "Many yochien [kindergartens] think it's too tough for small children to learn kanji," Matsumoto says. "We're taught we should write and read together, but here the children learn only to read kanji. We think with words, so children with a lot of words can express themselves richly."

Brown explains the method this way: "It's based on input flooding. Any direction the children look, they're getting kanji. The walls are covered with Chinese and Japanese poetry and kotowaza (wise sayings). Teachers flash kanji cards at the kids daily, and small children are very good at recognizing patterns."

Brown's English classes often resemble children's theater. Performances on both sides are fascinating. Brown has children act out stories with masks, props and costumes while she interacts with them. Trained in the Feldenkreis Awareness Through Movement method, Brown brings to her teaching a rich understanding of the way movement enhances brain development.

She also uses English vocabulary cards in games.

"To make it interesting, I hide the cards and from a corner of the card they guess what it is," she says. "They're really good. I don't think adults can do that.

"They learn very quickly and forget very quickly, so we try to make it entertaining for the children, presenting the target material under different guises, so children will repeat it many times with interest."

Brown notes that the children never make any conscious effort to learn. "They only do what is interesting. If they don't feel like doing it, they won't. That is the natural way of learning. There is no forcing."

Parents may be drawn to the accelerated pace of learning at Hikari Yochien, but it is interesting to note Brown's observation after 14 years of teaching:

"These children are slightly different. They seem to be gentler. The school founders seem to think that learning to read kanji gives the children a bigger vocabulary so they can express themselves better. You can reason with them."