Prince Charming/Advanced Sex Education

The following week, you're all sitting at your desks as she leads a young woman out in front of you.

"I want you to meet Annabel," the nun says. "She's fifteen years old and married with two children and she's kindly agreed to help us out with our lessons." She puts her hand under one of the girls breasts and lifts it. "See how her breasts have begun to droop a little, even though she's still only a teenager, and see how her nipples and aureola are quite dark compared with her pale skin." She moves on down the girl's body and shows off the stretch marks on her belly. "It's hard for a woman's body to stretch enough to allow a baby to grow inside her and some women end up with these marks."

She gets Annabel to sit up on the teacher's table and spread her legs apart and we all crowd round while she points out the different parts of her anatomy. "Pay particular attention to the clitoris," she says, and we hear Annabel take a sharp breath as the nun's finger stimulates her nub. "See how it swells up," she says. "Think of it as being a little like your cock. Some girls have big ones like Annabel's and some girls have really small ones, but if you want to please a woman or a girl, you won't go far wrong if you concentrate on their clits."

She moves out of the way and we all take it in turns to rub Annabel's clit. Roger sticks two fingers into her vagina at the same time, making her squeal and earning him a clip round the ear from the nun. By the time we've all finished, Annabel's face had gone quite pink. We all moved back and the nun looks up at her and smiles. "Some of these boys are probably wanking two or three times a day," she says. "Why don't you show them how a girl masturbates?"

Annabel giggles a little self-consciously and then puts her hand down between her legs to stroke her clit. She rubs her fingers down between her lips and then back up, spreading the moisture around. "See how wet she is," the nun says. "I told you about how pre-cum works with a man, now you can see the woman's contribution to making everything down there nice and slippery. Annabel is biting her lip and her fingers are a blur as she works herself up to a climax.

"Right," the nun says. "Let's have a look and see what you got in your shorts." You all look at her, and then, with a bit of giggling and nudging, you will drop your shorts and stand in line with your stiff cocks sticking out in front of you. She walks down the line looking at them and then starts rearranging the order. Lance goes down to one end and you go to the other, with Roger next to you. It dawns on you that she's put you all in size order.

There's a big bearskin rug on the floor and Annabel gets down on her back with her knees up and her legs apart. Lance goes first and gets down on his knees while the nun guides his little cock into Annabel's wet cunt. It takes about ten seconds before he starts gasping and pulls back showing that his cock is already going limp.

Each boy goes in turn; some take longer and for some, it's over almost instantly. Rogers cock is almost as big as yours and when it's his turn he looked round and grins at the rest of the class before ramming it in up to the balls. He bangs in and out really hard, and you're reminded of when you saw a buck rabbit fucking a doe. Annabel is making noises and thrusting back at him, but when you look at her face she doesn't actually look very excited.

Finally, it's your turn and you see Annabel stifle a yawn as you shuffle up between her legs. Her cunt is very slippery with a combination of her own juices and the boycum that some of the boys have deposited, and your cock slides in quite easily. She lifts her head to look at you as she feels the size of it and you start to fuck her slowly.

At first, she just lays there, letting you get on with it, when you reach down between you and find her clit with your thumb, you begin to feel her respond. With your cock sliding all the way in and nearly all the way out, and your thumb massaging her clit she can't help wrapping her legs around you. Without letting up on her pussy, you lean down and suck one of her big brown nipples into your mouth and start gently nibbling on it and that's the last straw for her and her hips start bucking underneath you and you feel her internal muscles clamping down to milk whatever they can out of your eight-year-old cock.

Your performance earns you a round of applause from the rest of the class and a hug and a kiss from Annabel. The nun, who watched the whole thing, tells you to stay back after class.

• You stay behind

• You tell her that you have another lesson to go to