When people ask me if I remember the first time I performed in public, I say: “Yes, when I was a teacher.”

I got my place on a PGCE at London University’s Goldsmiths College. “Wow,” I thought, “Great - I can go to London and stay away from Birmingham, my home city. I can avoid my parents and prevent an arranged marriage to some strange Asian doctor with no hobbies. I can go out every night. I can shop at Harvey Nics...”

No such luck. I was sent to an all-girls school that reminded me of the Army - except that there you probably get a lot more sleep . You soon realise that life outside teaching is diminishing. Nights out, friends, clubs, even Saturdays become things of the past.

The school looked fabulous when I was shown round. That was when pupils were in class and the corridors were empty. I soon realised that when pupils were dismissed, your life was at risk.The first exchange I heard when I entered a classroom to observe a lesson went like this: Teacher:

“Take that red cardigan off and put your chewing gum in the bin!” Pupil:

“No, you take your cardigan off, you silly cow.”

I’d been looking forward to seeing my first lesson. But the girls seemed to hate this teacher, who seemed to confuse being professional with being Hitler. But I soon learnt how bitchy teenage girls are. “You’re not a proper teacher, are you?” they’d say to me. “And you’re not a proper blonde, are you?” I’d reply. It always pays to have a good put-down.

I don’t think anyone can teach you how to teach. I learnt this when I entered the class armed with my well-rehearsed lesson plans, which went to pot when pupil “D” (for disruption) walked through the door. Some things you just can’t plan for.

My degree was in biochemistry, so in class the concept of the “pinhole camera” was news to me. In my first lesson, I had to teach a lesson about light. I knew a bit about light - I just didn’t know how to teach it. I had every textbook under the sun hidden under my desk in case, but I didn’t have a clue. I wrote the date on the board - that would be good start, I thought. Then I rambled on for ages. I told pupils my name (about three times). I fiddled with the light switches. I pretended to look for chalk. I wrote the title on the board, ‘Light’ (about three times). Anything to kill time. And it didn’t help that there was a proper teacher sitting at the back of the class who kept giving me funny looks.

There were lots of lessons like that. I guess you learn to teach by teaching. The more I did, the better I got. In time, I felt I could walk into any classroom unprepared and teach anything. But that takes time. Keeping control of 30 kids and trying to teach them as well is nerve-wracking, but it’s a great feeling when you feel you can do it.

It also takes time to get your head around ‘teacherspeak’ - TP, lesson plans, pastoral care, IEPs, differentiation... Awhole new language suddenly begins to spin around your head - and you’re likely to wake up in the middle of the night with these phrases on your lips. In one dream, I was summoned by a panel of teacher-judges. “How many pupils do you have in your class, Shazia?” they asked. “Differentiation,” I replied.

And watch out for so-called “professionalism”. Certainly, some teachers like to talk. Whenever I messed up lessons, I could hear whispers in the staffroom: “Not up to scratch...” “It was more like a ‘big hole’ camera, I hear...”

Being professional is crucial, but it’s not always clear what this phrase actually means. From my own experience, I would advise:

* Pretend to work hard at all times, especially when members of senior management are nearby. When they’ve walked past, you can go back to phoning your friends.

* Always stay at school late, but don’t actually do anything.

* Make sure your name is down everywhere - on the staff notice board, the day sheet, the newsletter. This way, it will look as though you’ve made a huge contribution to the school.

* Turn up to all staff meetings and departmental meetings and pretend you know what Inset means. Once you’ve demonstrated this, it’s safe to fall asleep.

Teaching was a great job, but a tough one. I thought stand-up comedy was hard, but after coming to it after teaching, I realise that it’s a doddle by comparison.

Shazia Mirza is touring nationally with her stand-up comedy show and starring in ‘Ten Things You Always Wanted To Know About Islam’, Wednesdays, BBC1, 11.35pm