Why Poetry Matters, BBC2Playing the Part, BBC1

Griff has little to teach us about poetry, while Denise Welch learns the hard way back at school

'I love poetry and I'd love to convince you that it matters," said Griff Rhys Jones in his wonderful cracked-mahogany voice, before embarking on an hour-long journey of non-discovery. Why Poetry Matters took in Waterloo station, Westminster Abbey, the old operating theatre at Barts hospital, the National Theatre and an ocean-going ship, but didn't actually get anywhere.

Rhys Jones is beguiling company as a presenter – passionate, thoughtful and skittish by turns – but his attempts to nail down the fugitive essence of poetry suggested a man herding cats. He pranced in a field of daffodils to satirise people's view of verse as "pansy and irrelevant" but his own counter-views veered towards the platitudinous: poetry can fire you up or calm you down; no word is wasted in good poetry; great poets are as rare as great film stars. We never learned why it "mattered", nor indeed what "mattered" meant.

He chased advocates all over the nation, soliciting their insights. Andrew Motion told him poetry should be difficult. Simon Armitage (inspecting a poem laid out in Scrabble tiles) said the best poets dealt in human speech as though talking to us. Nick Hytner at the NT explained the "emotional resonance" of iambic pentameter, and Ian McMillan, the bard of Barnsley FC, twinkled away in a street market and banged on about cheese sandwiches. Meanwhile, montages of school playgrounds, movie clips (the Auden recital in Four Weddings), TV stills and statues of Keats and Shelley kept the viewer in a febrile state of distraction.

There were surreal scenes – when Judith Palmer, the Poetry Society director, got a phalanx of bald geezers to recite Auden's "Night Mail" on a station concourse – and some touching moments, especially Griff's choking recital of Ben Jonson's poem to his dead son. But after all the frantic activity, the conclusion was weak: the "one universal value attached to poetry", Griff reported, was "people feel emotionally attached to it; it gives them such a kick". But so does a pet gerbil.

In Playing the Part, actress Denise Welch (Steph, the mouthy blonde French teacher, in Waterloo Road) returned to her real-life alma mater, Consett Community Sports College, to discover what real teaching is like. It was horrible. She had first-night nerves the previous evening: unable to make head or tail of words like "framework" in the curriculum, she decided to make it up as she went along. "I'd rather sleep with Paul Daniels than go through this," she wailed. "I'm worried about waffling if there's no immediate response."

She tried to communicate with the kids by asking their views of Kerry Katona, Britney Spears and their "dysfunctional" families, perhaps mistaking a class of Durham 12-year-olds for the readership of Grazia. The "immediate response" was a deafening silence that went on and on. In her next class, she suggested the pupils had "structured fun" with Cinderella, a decision that prompted wholesale anarchy. In the top GCSE English class, some anarchic youths discovered details of Welch's alcoholic breakdown on the internet and quizzed her about it, and afterwards, to her astonishment, became as meek and biddable as lambs.

It was a tough week, but made entertaining viewing. Learning that an Ofsted report on her teaching skills was imminent, Ms Welch elected to spend the evening before sinking gallons of sauvignon with her family. In class, she broke down mid-lesson and wept in the corridor. By the end, though, she'd grown more focused, thoughtful and calm, and learned a simple truth: you don't teach by acting like a teacher, but by letting the pupils learn stuff. The pupils, meanwhile, learned that some teachers can be weirdly human. A happy result all round.