All the teachers at St Munchin’s are really cool. I especially like Mrs Winkle, the head, but I’ve got a good reason for that, as you will see.

The only one who’s a problem is Mrs Cuffy, my science teacher. Actually she’s more than a problem. I think she hates me. And I’m not mad keen on her either.

I’m not the only one who feels this way. Mrs Cuffy is the nastiest teacher in the whole school and we’re all scared of her!

She has long, stringy brown hair just like rats’ tails, and a pointed twitchy nose. And, I swear, she has a straggly black moustache!

It’s bad luck that we don’t get on, because Mrs Winkle says I’ve got to get good at science. You see, Mrs Winkle knows something about me that very few people know.

She knows that I, Anna Kelly, am a witch! And the reason she knows this is simple. It’s because Mrs Winkle, as well as being our head teacher, is also a witch!

Of course I’m only a junior witch – an apprentice. But Mrs Winkle is an expert witch and she is helping to train me.

She says that science should be one of my best subjects. In fact, she says I can’t be a proper witch without natural science. I need to know all about plants and biology and why things in nature behave the way they do.

But there’s a problem: it’s boring! I don’t like science experiments out of books. I hate testing whether plants sweat and whether a coin is heavier than a cork in water.

Instead, I like doing magic experiments that come out of my head! And what I’m really into is a type of magic I can do called ‘shape-shifting’.

Shape-shifting is fantastic. No books, no test tubes. All you have to do is point at something, concentrate, and make up a magical rhyme. Then the thing you’re pointing at turns into whatever you want, like an animal or vegetable or anything!

So there I was last Monday afternoon, sitting beside my friend Mary in the science lab. I was gazing out of the window – and I was bored out of my tiny, weeny brain.

I was daydreaming about flying out of the window when suddenly a screech like a banshee shattered my thoughts and my eardrums.

‘Anna Kelly!’ shouted Mrs Cuffy. ‘Come to the front this minute!’

I shot up straight in my seat and met Mrs Cuffy’s beady little black eyes. Mary looked at me sideways.

‘You’re for it now,’ she whispered.

‘Thanks,’ I said.

Mrs Cuffy stood at the front of the class with her thin lips curling in disgust. In her hand, she held one corner of a dirty piece of paper, waving it about as if it was an old snotrag. I took a deep breath and dragged myself up to face her.

‘And what,’ she shouted, twitching her moustache, ‘do you call this?’

‘My homework?’ I said.

‘Cheek!’ she snapped. ‘Detention tonight for being cheeky!’

I gasped. I wasn’t being cheeky! The snotraggy-looking scrap was my homework – it wasn’t my fault it ended up looking like that. My cat Charlie had eaten his dinner off it when I wasn’t looking.

‘But Miss,’ I said. ‘It is my homework. Look!’

I pointed at the untidy squiggles that were meant to be yet another experiment about the effects of vinegar on eggshells. It wasn’t very good, but I’d done my best.

‘Anna Kelly,’ said Mrs Cuffy. ‘This is meant to be a simple science experiment about weak acids, not an explosion in a catfood factory! You’ll write it out again after school – twice! Sit down!’

I trailed back to my desk and sat down. It wasn’t fair. Out of the whole class, she always picked on me – and I was sick of it! Mary squeezed my arm and smiled at me in sympathy. The bell rang for the end of class and everyone leapt out of their seats.

‘Freeze!’ shouted Mrs Cuffy, and everyone froze. ‘Mary Maxwell, you will stay behind for smirking at Anna Kelly. The rest of you may all file out in an orderly fashion!’

Mary’s mouth fell open in shock.

‘But I … but I wasn’t smirking!’ she stammered.

‘Double detention for cheek!’ shouted Mrs Cuffy. ‘Go and see Mrs Winkle right now, and tell her I sent you!’

Poor Mary went bright red and her eyes welled with tears as she walked slowly out of the classroom in front of the hushed boys and girls. She was supposed to be in a gym competition tonight, and now she would miss it – all because of rat-faced, whiskery Mrs Cuffy!

And that was what did it. That was what finally made my blood boil. I’m not proud of it, but there and then I decided to do something drastic. I was going to teach Mrs Cuffy a lesson!