Clutching a gaudy homemade doll in flames, students gathered Thursday on a frosty footbridge in central Poland to toss it into the river -- an ancient rite repeated across the country every March 21.

Chanting "Evil winter begone!", the students joined winter-weary Poles nationwide in the centuries-old tradition of burning "Marzanna" dolls to cast away the cold, illness and all other misery.

"The initial plan was to drown one of the girls from class, but our teacher said no," joked Piotr Soldanski, 14, drawing laughs from his classmates in the town of Sierpc.

The students made their Marzanna doll out of everyday items: colourful ribbon for hair, crumpled newspaper for the body, a parent's old shirt for the headband, a mop stick for support.

"The Marzanna is supposed to be ugly. Because it symbolises misfortune," said Joanna Szewczykowska, who organised the event at the local folklore museum, the Muzeum Wsi Mazowieckiej.

The origins of the word "Marzanna" are under debate, but the etymology is clearly rooted in a vocabulary of misfortune.

Szewczykowska says the name harks back to the word "mor", which means "illness" and is no longer used.

Her colleague Robert Piotrowski, an ethnographer, links the name to the word for "she died": "zmarla."

To complicate matters, the doll's name has had variants over the years and across regions.

Many Marzanna dolls today are eye-catching numbers full of colour and creativity.

At the Zastow community centre in Warsaw, the 80-some dolls on display along the fence included faces made of rubber gloves, arms made of wooden spoons, button eyes and garlic garland necklaces.

"We're thinking of doing a green edition of the Marzanna contest," said centre employee Olga Gradzka, 44, pointing out eco-friendly items among the rainbow lot.

Traditionally, going back centuries, the doll was made of straw, the most readily available material for country dwellers desperate for spring, Szewczykowska said.

"Until the 19th century, this rite was taken very seriously and was carried out by adults.

"But since then, it has turned into something fun for kids," with bad grades one of the chief ills to chase away, she said.

Teachers plan the torching and drowning event as a field trip, since March 21 is also Dzien Wagarowicza, or "skipping school day", when students cut classes to seek out spring, forcing police officers to patrol for truants.

"Better to organise something official, rather than have the students come up with some outlandish plan," said Alina Dumowska, 56, the Sierpc students' English teacher.

After throwing snowballs into the river for good measure on Thursday, the bundled-up teenagers watched the smouldering doll float away.

Then they turned to part two of the rite, the "Gait", in which they paraded down the road carrying a pine-tree branch adorned with colourful tissue-paper flowers to symbolise spring.