"Donald, come here this minute."

The strident voice of Margaret Mackie hammering up the stairs broke the tranquillity of Donalds bedroom. The fifteen year old rolled over and clambered off his bed, wondering what he'd done wrong this time. He quickly ran through his current thoughts and actions and could find nothing for which he should be worried.

Still puzzled he made his way downstairs. Ever since his father had died three years ago his mother had become more and more waspish and, as far as he could see, it was all aimed at him. Therefore when she summoned him he was always quick to respond.

The staircase descended into the dining room, completing his descent Donald found his mother sitting at the dinning table. She'd only been home from her job as an accounts clerk for ten minutes so she was still in her works clothes. The neat white blouse, buttoned to the neck, and the calf length straight skirt, that hugged her slender figure, made her look like a strict school teacher.

The way she was sat, stiffly upright, with an official looking letter firmly clutched in her hand made her even more imposing. She glared at him as he approached across the neat axminster carpet.

"What is the meaning of this?" she asked, causing the letter to flutter in her hand.

Trying to keep calm Donald asked, "What is the meaning, of what, mother?"

"This letter your sister has had to bring home concerning you. " She said, her voice becoming shrill, as she waved the letter in front of him. "You've failed the anatomy module of your biology course. How could you?"

Donald stood there a looking confused, his biology course did have an anatomy module but that was last year and he'd passed it with flying colours. He knew his mother had been driving him hard to improve his grades. To her, being in the top ten percent wasn't good enough, he had to be top. So a letter alleging he'd failed something would be a hammer blow, but it didn't make sense, he hadn't failed.

Before he could get his brain into gear and say something his mother continued. "Fortunately for you the school have agreed, because your record so far has been exemplary, to let you re-sit the module and if you pass then no record of the failure will appear on your transcript. Do you understand, you've got another chance?"

Donald, still confused by the turn of events, could only nod his head in agreement, 'what on earth was going on here?'

Margaret turned towards the front room doorway and called out, "Helen, come in here now."

Helen, his older sister appeared from the front room, where she'd obviously been waiting for this summons, a smug grin in her face.

"Yes Momma."

"Come here," Margaret said, indicating a spot between her and Donald. Helen moved forward and Donald watched on, wondering what this had to do with him, the rapid turning of events keeping him completely off balance.

"As you know, after all you did bring the letter home, Donald has a problem at school. We," she emphasised, "are going to do everything in our power to help him through this difficulty, no matter how embarrassing or demeaning that is. Don't you agree?"

Helen still had that smirk on her face as she nodded, "Yes Momma."

Now Donald knew he was in trouble, Helen only ever called their mother 'Momma' when she was getting her own way, and she'd said it twice already.

"Your little brother has failed in class, his anatomy class of all things, so we are going to use your body as a practical teaching aid to further his education." Donald blushed, he really couldn't fathom out what was going on and it was getting more embarrassing with each passing sentence, he glanced at his sister to see how she'd taken the pronouncement.

Helen didn't seem in the least bit surprised at that announcement, Donald on the other hand was sinking further into shock. If he'd understood correctly, and he didn't think this was a dream, his mother was going to expose his sisters body to him, to further his education. NO WAY!

Donald looked from one to the other of the women, and lets face it, at seventeen Helen was a woman for all practical purposes, and they looked deadly serious, surely this was a joke. He tried to form the words to express his opinion but his mother carried on, right over any objection he was going to make.

"Now Donald, I want you to go and get your text book on the subject and bring it back here."

Donald didn't move, his brain had just quit sending orders to the rest of his body. "Donald! Move your lazy body." His mothers sharp words broke through his daze and he turned for the stairs.

As he started to ascend he heard his mothers voice in the background, "Helen, I think it would be better if you did this in the privacy of your own room." Donald slowed his pace, listening, trying to get a clue as to what was happening.

"Momma, it wouldn't be right, you need to be there, at least to start with, just to make sure I'm doing it right." His sister moaned.

Doing what right? Thought Donald, stationary now on the staircase.

"Maybe your right Helen." His mother paused in her reply. "Yes you are. So what we will do is this. We will get you undressed here, I will take Donalds text book and call out the names of various locations. Donald can then indicate, on your body, where they are."

Donald just managed to suppress a gasp, all the earlier comments made some sort of sense.

"If Donald does well I will allow the two of you to go up to your room to continue the studying. That way you wont be embarrassed if anyone should come calling."

She wont be embarrassed, what about me thought Donald as he resumed his ascent of the stairs. One thing had changed though, after eavesdropping on the females of his house he had found that a lot of his anxiety had been left behind. He still didn't understand fully what his mother and sister hoped to achieve, but at least he had an idea of how they intended to achieve it and that was one thing he was willing to go along with.

Returning to the dining room, the schools anatomy text clutched in his right hand, Donald pulled up short when he saw his sister stood before his mother. That was how he had left them but now his sister was stood in just her plain white underwear. A quick glance around the room showed the rest of her clothes neatly laid over a spare dining chair.

Resting on the dining table, across the mysterious letter that had started this strange chain of events was a bamboo cane. The sort of cane that his mother used to tie up plants in the garden and the sort of cane that could be used to inflict punishment. Was that what this was all about pondered Donald.

Before he could take any further action he was spotted by his mother, who immediately beckoned him forward. "Donald, find the section in the book on female anatomy and give it to me." She demanded, "Then take this stick," she picked it up off the table and waved it in his general direction, " which you'll be using it as a pointer and get over there next to your sister."

Donald flicked through the book finding the illustration that he and his friends had poured over long
before the lesson was due and passed the open book to his mother. Carefully he took the cane from his mothers hand and turned towards his sister. He couldn't help but look over the body of the maturing young woman.

Although he'd had a vague impression that his sister was pretty fit this was the first time he'd actually looked at her nearly naked form objectively. Her mousy blond hair was fairly short, she said it made it easier to care for it, but it framed a pretty face nicely. Her body was well toned from all the swimming she did but she hadn't gone flat-chested like some of the gymnasts he knew.

Interrupting his thoughts his mother began, "I'll call out a location Donald and you will point at it using that cane. Once we've been through them once I will let Helen take you upstairs so that you can continue in private. Be warned young man, if I am not satisfied with your performance then that pointer will find another use, a use you man not be very appreciative of.

Donald flicked the cane from side to side, listening to the noise it made as it passed through the air. It didn't take much in the way of imagination to feel the shock of impact on his softer regions. He took a deep breath to steady his nerves and then noticed the way that the nipples on his model had surprisingly, sprung upwards.

"Right, we'll start with the basic skeletal structure. Donald, all you have to do is point out where the following bones are in the body."

Donald moved position slightly so that he could clearly see his mother, who had the book open on the table and was studying it nearly as hard as he had.

"Clavicle."

Easy thought Donald bringing the pointer up to his sisters collar bone.

"Sternum."

The boy allowed the pointer to drift across his sister body until it rested neatly on the centre of her chest. He'd been very careful not to touch either of the breasts encased in the soft sports bra that Helen had on.

"Humorous."

The funny bone, thought Donald and quickly indicated the upper arm. What followed was a trip around the body which really caused Donald no problems, Ribs, Femur or thigh bone, Patella, the knee cap, then the pairs. The Radius and Ulna in the lower arm followed by the Fibula and Tibia, the corresponding bones in the lower leg.

His mother followed up with the two groups of small bones, the metacarpals, or fingers and the metatarsals or toes. He had Helen turn around when his mother asked about the spine.

Then he slipped, not so much in the answer but with the pointer. "The Coccyx?" Asked his mother. Helen giggled as Donald bought the pointer down harder than he'd planned on the top of her bum. The sting shot his sister upright and silenced her. Donald, to embarrassed to even apologise, adjusted his aim until he was pointing at the base of her spine.

Surprised at the lack of response Donald dragged his eyes off the table top and noticed that his mother was flushed but silent. She flipped over the page in the text book and studied it.

"Soft tissue groups including muscles," intoned Donald's mother.

Donald swallowed, it had been a long time since he'd gone through this and he wasn't sure he could remember everything he'd memorised for the original test. Still he'd better do his best as his mother clearly wasn't going to accept any excuses. Or, he thought, any explanations how this was all a big mistake.

"Biceps, Deltoids..." the list went on containing all the major muscle groupings.

"Gluteus Maximus." Once again Helen let out a little chuckle. Donald, who had been getting more stressed with each question allowed the cane to make sharp contact with his sister's, wonderful he admitted to himself, arse. Another sharp intake of breath all round and a pregnant pause before his mother continued.

"Trapezius Muscle."

Shit, thought Donald, where the hell is that?

His mother, used to Donald's prompt replies watched, fascinated, as the cane described smaller and smaller circles and then, like a snake striking, shot out to the back of Helens neck. "There."

"Well done. Now we'll move on to something you probably know without the book."

Donald watched as his mother, then his sister, flushed a delicious shade of pink. Surely she's not going to ask me about...

"Helen."

"Yes Momma."

"Remove the rest of your clothes."

Donald shot his glance from his mother to his sister, who smiled serenely at him and reached for her bra. Donald didn't know whether to look or not but finally hormones won out against modesty. Helen peeled the soft sports bra over her head and casually tossed it onto the pile of clothes. Her bust was of moderate size decided Donald but more than adequate. Helen smiled at her bemused bother then bent forward, straight legged, to drag her sensible white knickers down her legs.

Donald swallowed hard and turned to face his mother, half fearing what he would find.

His mother seemed to be as fascinated with Helens body as he'd been.

He caught the flicker of motion in the corner of his eye as Helen threw her knickers onto the pile of clothes and waited. His mother looked down at the text book and called out, softly, "Areola"

Donald couldn't stop his hand shaking as he raised the cane to his sisters pert boob. Her areloa was a deeper brown than the rest of the boob. Getting the pointer to touch it without touching the nipple was hard, so hard he felt like grabbing the cane with both hands to steady it.

He noticed that his breathing was nearly as harsh as his sister's. He could actually see her nipples pulsing in time to her heart beat.

A disembodied voice rang out, "Correct, now the mammary."

Donald breathed a sigh of relief which caused him to lose control of the pointer. Which, in the way of these things, rose slightly then dropped down, tapping Helens breast. She moaned in a most peculiar way but before Donald could apologise his mother called out, "Correct, now the rectum."

Without even being told Helen turned around and bent over, pushing her hands back to grip the firm globes of her gluteus maximus. Donald, mesmerised by the sight of his sister's pert derriere had to be reminded what he was looking for.

"Point out her rectum, Donald."

"Spread your cheeks Helen." Said Donald, softly.

Helen looked over her shoulder at her brother and gave him a strange, challenging, look.

A look that Donald interpreted as 'make me'.

Without saying another word Donald flicked the cane upwards, striking the lower part of her cushioned rump. He'd taken great care to avoid her fingers and hadn't swung at anything like the force needed to cause any damage.

He was surprised then when his sister sobbed before pulling her bum cheeks apart. Her rectum was revealed, the pink orifice tinged a light brown colour. Donald expected his mother to move on but she didn't, he glanced over at her and she raised an eyebrow back at him.

Taking another deep breath Donald touched the little puckered opening with the very tip of the cane and was rewarded by his mother. "Correct, now a nipple."

Helen released both cheeks, nearly trapping the cane between them and spun around, rising from the bent over position as she did so. Donald could have sworn she was pushing her chest out as far as it would go. There was no chance of missing her nipples, they were as hard as any he'd ever seen.

As he started to raise the cane to indicate the delicate pink protrudence Donald had a eureka moment. Without thinking he followed through on the thought and swept the cane up, striking the nipple as he passed, then bought the cane down until it was resting on the throbbing object.

He held his breath waiting for some sort of response. When none was forthcoming he rolled the cane off the top off the nipple and bought it up sharply under the other breast, saying as he did so, "This is a nipple, as," he swept the cane through the second nipple, causing his sister to hiss, "is this," he concluded. Resting the cane on top of the second nipple.

After a very long pause his mother called out breathlessly, "Correct, two items to go. Where is the vagina."

Donald was lost in the game, a game he didn't even know he was playing. He drew back the cane then bought it forward until the very tip was touching his sister's pussy, a pussy that his nose informed him was a little excited at the current proceedings.

"Correct, now the labia."

"Open up Helen."

His sister refused to look at him and he watched as she pushed her knees closer together. He drew the tip of the cane back six inches and flicked it back against her thigh.

"Now please," he said, firmly.

Helen looked at him and Donald couldn't decide whether she was asking him to stop or to go on. Running the whole scene through his mind he guessed that she wanted him to go on, so he drew back the cane again and bought it down much more firmly across both of her thighs.

"Squat! Now!" He barked at her.

Her knees shot out and her whole body dropped towards the floor, stopping with her pussy only inches from the carpet.

Calmly, Donald set out to correct her position. "Too low Sis, come up at least six inches."

Without any hesitation Helen rose up, her pussy lips, glistening, clearly on display.

Donald placed the tip of the cane on the moisture and slowly rotated the cane before looking over at his mother.

He was staring at her face when she dragged her eyes away from her daughter's exposed body and looked into her son's eyes. "Correct."

Margaret gently closed the book she'd been reading from and looked at her children. Helen had stood up and was rocking from one foot to the other, Donald still had the cane firmly clasped in his hand, its tip glistening with his sister's secretions. Both of them were staring at her, waiting for there next instructions, unwilling or unable to proceed.