Last Night's Television: Playing The Part, BBC1My Weapon is a Dog, BBC3The Home Show, Channel4

Chalk it up to experience, Miss

"You used to be an alcoholic, Miss! Miss, it says you went to Alcoholics Anonymous! Is that true?" Ah, the joys of Wikipedia. Lesson One: don't take your class into the computer room and let them surf the web. Especially not if you're a semi-famous, middle-of-the-range TV actress like Denise Welch trying to enlighten a room full of unruly teenagers as to the joys of photojournalism.

It's not as if it's all true, anyway. For starters – I've just looked her up myself - it says that she doesn't drink, which, ahem, she clearly does. Often. So often, in fact, that I suspect some creative editing may have occurred. That, or... well, or she just drinks a lot: First day at work. Gulp. Just what I needed. Gulp. Am I drinking alone then? Gulp. Hm.

In the first instalment of Playing the Part, she was spending a week at her old school to see if pretending to be a teacher – she plays the lackadaisical French teacher Steph Haydock in in Waterloo Road – is anything like actually being one. It's a clever idea. Teaching's one of those professions that everyone reckons they'd be good at, in the kind of "I could do that if I had half a crack" sort of way, but which, when you're the one doing it, suddenly doesn't seem so simple (see also acting, cooking and, um, journalism).

Denise, it's fair to say, did an admirable job in proving how very un-simple the whole thing can be, rolling from one crisis to another with ever ring of the school bell. Her first class refused to talk, her second ran riot, her third appeared to take the lesson into their own hands and her fourth started delving into her Wikipedia page. Even the pupils started offering advice: "She needs to tell us off more," mused one wide-eyed eight-year-old. By the end of day two, she was in hysterics and running out of the classroom, pushed over the brink, apparently, by a comparative exercise involving the Sun and the Independent (enough to send anyone a little doolally).

Things didn't get much better from there: at one stage she overslept, missing her first lesson of the class. "I'm poorly," she explained, not entirely convincingly. At least, I suppose, she was a good sport. After a day with those brats, I'd have walked out too. Not the kids – they are all rather delightful – but the teachers: judgmental, prissy, and bureaucratic, offering no advice whatsoever, just lesson plans packed with incomprehensible jargon. "They don't understand," pleaded Denise to a passing Ofsted inspector. "I'm an actress!" Poor woman.

Over on BBC 3, the Youth of Today were getting a rather worse rep, courtesy of My Weapon Is a Dog, a suitably alarming documentary on the UK's sudden rise in dangerous dogs. Actually, I know this about this. I've been moaning about it for months, like some foul-tempered pensioner. They're everywhere: hogging the pavement, straining and flexing on their chain-mail leads. They chase you when you run for the bus and snap around your heels on the high street. It's clear why these kids have them, I suppose: no one wants to walk within 10 feet of them, let alone pick a fight, but it's all terribly depressing nonetheless.

Kiss FM's Rickie Haywood-Williams did a good job of presenting the problem, interviewing various dog owners and breeders (or canine lonely hearts, as I like to call them: "You're dog looks just like mine, wanna meet up?'") and talking to Rukhsana Kahn, the 23-year-old woman whose childhood mauling by a pit bull terrier ushered in the 1991 Dangerous Dogs Act. A visit to Harmsworth Animal Hospital in north London was the low-point. They were inundated with beaten-up little puppies, discarded by breeders because of some minor defect. It's not clear how the problem can be solved. Unhelpfully, Defra, the Government department for environmental protection, refused to grant an interview, so for the time being, dogs looks set to follow knives as the teenager's weapon of choice. In fact, I predict a rash of headlines around this time next year: "Dog Crime Crisis Grips Britain". So goes the cycle.

Fractionally more uplifting was The Home Show, back for a second series after several months away. When it first burst onto our screens, you remember, it was presented as a sort of recessionary antidote to the money-grabbing likes of Kirstie Allsopp and Phil Spencer. Instead of hunting for another location, location, location, contestants – if that's the word – were encouraged to make do and mend, with the help of the architect George Clarke. Still, it's not exactly homes on the cheap. Last night, Alicia and Antony spent over £120,000 on renovations, less expensive, perhaps, than buying a whole new property, but more than most could afford.

Speaking of which: ever taken the bathroom-sink personality test? George can personally vouch for it. Clean lines and marble: you're not impulsive. Bling? You're an extrovert. Something classic? "Anti-trend", a euphemism for something no doubt. I, in case you're wondering, am the latter.

a.jarvis@independent.co.uk