Mr Foster, the biology teacher at Central High, had heard about the "field day' held at the school where an old collage pal taught biology. He was intrigued with the events in the resulting biology lesson and wondered if they could achieve a similar success here.

He rapidly worked to convince the principle about the idea to have a 'Central High Sprit Day' to build some support for the school sports teams, it was easy to get the Phys Ed coaches to support the idea but he'd kept quiet about the events in the biology class. With the head coach pushing the idea of all the students showing support for the schools teams by spending the day in their sports kit, the head approved the idea immediately.

Planning ahead he had arranged the day to be one of the next times when he had the senior class for biology and had spent some time planning who to manoeuvre into volunteering for the demos. Getting one of the boys in the swimming team should be easy as a number of them were quite exhibitionist. Also there were a number of the girls in the class that often acted to show off their bodies, sometimes making him get hot under the collar.

The appointed day was a couple of weeks away so he re-arranged his teaching plan to put the human anatomy section in the lessons leading up to the day to provide a lead-in for it.

During the lessons in the intervening time he dropped a few hints about using some live models and watched to see who reacted, both positive and negative.

As the day got closer Mr Foster decided the best option for the male specimen would be Rich Olivey, he had a well developed musculature, useful as the excuse for getting him involved if needed, and he always had a number of girls around him so was not afraid of showing off. The female was more difficult, there were a number that, according to the rumours, were no longer virgins and, if they were going to get the same participation as his collage pal had got, the girl would need to be a least a bit experienced. He decided the one he could most likely catch was Marketa Decker. She was a bubbly blond and was always talking in class and whenever he asked questions was one of the first to jump in with comments. It wouldn't hurt that she was also one of the cheerleaders so was used to performing in quite revealing clothes.

The story of the events at the other school showed the astounding success was the inclusion of one of the more reserved boys in the demos. In fact picking an obvious inexperienced and possible virgin, who had a crush on the girl, seemed best. Mr Foster decided this would have to be sorted on the day when the rest of the class was reacting to the unfolding events.

School Sprit Day

The day arrived and, as expected, the coach had convinced the swim team to push the limits by only wearing their very brief trunks for the boys and high cut costumes for the girls. The rest of the students had also complied with the request to only wear sports kit and many of more adventurous students had heard about the plan for the swim team to be as revealing as possible and had joined in with the briefest possible kit. The cheerleaders had picked their most revealing outfits.

After lunch when the senior class arrived at Mr Foster's biology lab, he had the front setup with the human anatomy diagrams hanging above and to the side of a table. This caused numerous groans from the class.

Mr Foster entered and called the class to order. He said "Quiet down, today we are going to cover the remaining parts of male and female anatomy, and I want to start by stating this is a serious subject and I don't want anyone to feel embarrassed by it."

"You have all seen the diagrams at the front but have no doubt noticed there are limits to the data shown. Following an experiment tried by a friend of mine we will try and overcome these limitations."

"To that end I would like to ask one of the boys in the swim team to help us by filling in some of the missing data by acting as a living model for us. Having them in just their swimming briefs will certainly help as they are already stripped so to speak.

"Mr Olivey, would you be willing to help us in this matter?"

Rich Olivey was somewhat startled at his name but being one of the natural show-off types could not decline the chance to pose in front of all the girls in the class in so little. He rose and moved to the front with a grin.

"Before we start a few rules for the following, your participation in much appreciated and is totally voluntary. If at any time you want to call a complete halt or to decline any part you are free to do so and all credits earned up to that point will remain, however the more we do the more credits are available, just to give a bit of incentive to the participants. We'll see who else we need as we progress, so others will have the chance for additional credits as well."

Mr Foster told him to stand on the table beside the diagram. He then turned to the class and said "Right now we have a real model what are the difference between Mr Olivey and the diagram? Any suggestions"

A number of students raised their hand but, making Mr Foster smile inside, Marketa Decker just called out, "All the interesting bits are still covered."

"Well Miss Decker thank you for volunteering, perhaps you can be our demonstrator and provide the necessary information to complete the picture."

Marketa stood and somewhat hesitantly moved to the front, her normal bravado knocked back by her uncertainty at what was coming.

Mr Foster handed her a long pointer and said "Right our temporary lecturer, Miss Decker, will now indicate the salient points of the human male body using both the standard diagram and the live model. I would ask her to be careful not to damage either, I'll need the diagram later and suspect Mr Olivey would prefer not to suffer any pain or lose any of his facilities."

His words caused a ripple of laughter in the class and a big nod from Rich.

Marketa started, pointing to the face of the diagram saying "Working down from the top, the diagram fails to show the facial hair that appears on an adult male and which either is left as a beard or is shaved off every day. Personally, having had a relative with a beard, I prefer a clean shaven face to either kiss or be kissed by; a beard is rough and tickles."

Pointing to Rich's face and gently tapping on his cheek she continued "Rich either already shaves or has yet to develop these yet. Which is it Rich."

Rich grinned and said "Well at the moment I shave every couple of days, I did so this morning so it doesn't show much today"

Mr Foster spoke up asking "Anyone like to explain the significance of that."

A voice from he back called out "Means he's making testosterone!"

Mr Foster said "Well, if our well informed speaker had bothered to wait to be asked, he or she would have gained a credit point for today's lesson, but as they couldn't wait they forfeit it. This is a serious lesson not a free for all."

"OK Miss Decker please continue"

Pointing to the chest of the diagram and then Rich's chest she said "Another indicator of the maturing male is the hair that normally appears here. I expect that as Rich is a competitive swimmer he removes this to reduce drag in the water."

Turning to Rich she asked him to make the muscles of his abdomen standout.

"These are the muscles that in the diagram would cover the internal organs shown in the cut away section. Also here is the belly button which marks the position where the umbilical cord was attached."

Turning to Mr Foster she said "I can't show the rest as they are still covered on the live model and are not shown on the diagram."

Mr Foster stepped back to the front and said to the class "Right here's the point we need to make a joint commitment, if any of the class feels they are uncomfortable with the way this is likely to go they need to let me know now."

"Also since some of those that will be asked to participate may be uneasy with the idea of the rest of the school hearing about what may occur, everyone and I mean everyone, has to agree to keep what happens now private to this group. By that I mean you can discuss it with others in this class but not those outside it."

"Remember these are your friends and colleagues so betraying this agreement is going to hurt those who are helping you learn and it may be you that is asked to perform later."

He paused to see if anyone spoke up but no-one did.

"Right, from this point forward it is important that we all exercise restraint and remember that all the class members performing are people and not just animated mannequins."

He then turned to Rich and said "Are you willing to continue?"

Rich looked at him in disbelief and said "Do you mean standing here completely naked?"

Mr Foster confirmed that it would mean doing that.

Rich thought for a moment and said "I get extra credit for this right"

Mr Foster confirmed "Definitely"

"OK I'll do it" which made a number of the girls in the class gasp in surprise.

Mr Foster said "Do you want to strip yourself or let someone else do it?"

Rich replied "I'll strip myself, its scary enough doing this without having someone else doing it; I've never done anything like this before."

Marketa, her normal outspoken manner re-surfacing, couldn't help but say "Shame I was hoping to get that job", much to the classs' amusement.

Rich stripped off the brief trunks and stood up straight again, his cock hanging down partly aroused but also partly depressed due to the unusual conditions, which had both aroused him and caused an almost panic induced retraction.

Mr Foster turned to Marketa, who was staring at Rich's cock with interest, and said "Right Miss Decker, it's now all uncovered, ready to continue?"

Marketa jumped on hearing her name and swallowed a couple of time trying to regain her composure, then taking the pointer pointed to the hair around Rich's cock and, taking a deep breath said "A further sign of maturing in the male is the development of pubic hair" as she said this she started trailing the pointer around in the relatively spares growth, gently rubbing Rich which caused his cock to start to rise up as he became more relaxed and used to the situation.

Mr Foster had to tell Marketa "Please concentrate Miss Decker, we have more to get through."

Marketa jumped again and, using the pointer with great care, lifted Rich's cock to enable everyone to see his balls. Looking back to the class she said, "This is where the important stuff comes from, the testosterone that triggers the changes in his body to enable the male sexual responses and also the source of the sperm to impregnate a female."

"I see that the attention has caused Rich to become aroused and show the male in a state ready for the sex act. As you can see the penis extends to be ready to be inserted in the female vagina, and the clear liquid being slowly produced has two uses, the first to clear the channel in the penis to make sure there is no urine left and the second to help lubricate it during the initial entry."

Mr Foster, following the events that he had been heard about, spoke up, asking the class, "Who can tell us the approximate quantity of fluid that a male produces during a climax?"

A number of the boys raised their hands but Mr Foster said, "We'll let the ladies take this question, gentlemen. Anyone care to make a suggestion?"

When none of the girls raised a hand he said "No one willing to even guess?"

"Mr Olivey, would you be willing to help the ladies with a practical demonstration."

Rich looked at the teacher in shock and said "Are you serious!"

Mr Foster said, "This is a serious scientific lesson intended to give all the class an accurate understanding of the human anatomy and male to female interactions, so yes I'm serious. Would you prefer to do it yourself or have someone help you, it"s your choice. If you"re not willing to perform this I"ll ask for another volunteer to provide the demo.'

Rich asked "Who would be the person to help, assuming I agree?'

Mr Foster said "Well, it"s up to you, you could ask for help from any member of the class, but I would point out there is one person already up there with you who has shown a willingness to participate and was disappointed you didn"t get help in stripping off.'

Rich said "If Marketa is willing, I think I can go with it.'

Marketa stood there in shock; it had now been dropped on her, could she do it. She had only given one of her dates a hand job before and that was in the dark. She hadn"t known really what she was doing but he had seemed to enjoy it. Although she wasn"t a virgin, her total experience was one hand job and one time of full sex when she lost her virginity. Her persona of an experienced sexual partner was really a front to hide her nervousness in dealing with boys.

She swallowed hard and putting her public persona in place to hide her uncertainty said, "I would be happy to assist Rich.'

Mr Foster passed her a measuring flask and said "When you are ready please, try not to lose any so we get an accurate level.'

Marketa climbed onto the table next to Rich and looking him straight in the face and very quietly said "You OK with this really?'

Rich just nodded slightly and smiled at her and said "Ready when you are.'

Marketa wrapped her hand around the stalk of Rich"s cock and started rubbing it up and down, somewhat hesitantly. Rich leaned over and whispered "You can grip a bit tighter without breaking it if you want and if you rub the head it will bring me off quicker.'

Mr Foster said to the class, "There is one of the most important points in any sexual encounter, everyone is different and the only way to make sure you both get the best from it, you need to let the other know what is good and where they are not doing it right. Mr Olivey just let Miss Decker know the way to increase his pleasure without making her feel she was doing anything wrong at the start. Most likely Marketa"s previous partners had liked it very gentle, so since she did not know Rich needed a tighter grip she did not grip tight.'

Marketa kept her face neutral, not wanting to admit that she had so little experience it was not that the previous partners wanted a light touch but was really that she had no idea what she should do, the previous time it had just happened and he had been so worked up it had hardly needed her touch to bring him off. She was staring at Rich"s cock with her hand around it, totally fascinated.

After a couple of minutes Rich started breathing hard and he said "Quick, get the flask, I"m coming any second now!'

Marketa had almost forgotten about the flask, but grabbed it and managed to catch all in it, squeezing and milking the fluid into it.

Rich steadied himself by holding Marketa and leaned over and kissed her on the cheek and said "Thank you that was outstanding.'

Marketa then read out the measure to the rest of the class, she had to hold the flask up close to see the graduations and while doing so could smell the odour for the first time this close.

Mr Foster said "Right I think that covers the missing parts of the male anatomy. Let"s move on to the female. Miss Decker do you want to continue or stop, before you decide, Mr Olivey are you willing to continue and do the pointing for Marketa.'

"Go for it Marketa" Rich said, "I'll be careful with the pointer."

Marketa still a bit overwhelmed by the events so far nodded without giving herself any time to panic.

Mr Foster seeing she was a bit nervous decided to push ahead as quick as possible before doubts caused second thoughts. He said "Do you want to strip yourself or let Rich or someone else do it."

Rich leaned over and whispered "Let me do it please, I should have let you strip me, I'll make it fun and it will get you relaxed, I can tell you've not done it many times."

Marketa just said "OK do it before I have second thoughts."

Rich gave her a quick peck on the cheek and standing to the side so as not to block the view proceeded to remove her cheerleader dress, leaving her in bra and the shorts she wore beneath it. Moving behind her he disconnected the bra snap slowly saying, "I normally do this from the front so being able to see what I'm doing is making this very difficult." Which made the class laugh and even Marketa laughed, forgetting that her breasts were about to be revealed to all her classmates.

Rich dropped the bra down her arms and stepping round to the side again gave a low whistle and said "God Marketa you're beautiful."

Marketa blushed from her waist up to her face. Rich dropped to his knees close to her and reached to remove her shoes, and having removed them reached up to her waist and gently and slowly pulled down her shorts and lacy pants in one move. As they cleared her pussy the fine blond pubic hair did nothing to hide it and Rich looked over his shoulder to the rest of the class and said "I was wrong before, this is real beauty."

As Rich got the shorts and panties to the bottom of her legs Marketa had to steady herself on Rich as she raised each in turn to step out of her clothes, giving Rich a close up view of her pussy lips.

Once done, Rich jumped done to stand below Marketa, leaving her alone on the table beside the hanging diagram. Then taking the pointer, tapped the diagram to call the class to order. When they quieted he started by pointing to the stylised breasts on the diagram and said "The breasts on the diagram are shown as just blobs, but in real life they are, as our beautiful model shows, a superb part of the female. As Marketa had pointed out on me, the male grows hair as one sign of maturity, in the female the mammary glands develop ready to provide milk for the young. The breast has two major parts, the main body and the nipple area, both are quite sensitive and during foreplay and sex the nipples become very aroused and sensitive."

As he talked about these he was rubbing the pointer around and across each, and each time he did so Marketa jumps and her breath quickened.

He then moved the pointer to the area below and said, "unlike the male most women don't have a set of muscles that create the six-pack effect, the muscles of her abdomen are designed to stretch to allow the baby room to develop."

As before, he kept the pointer moving just in contact with Marketa, causing her to feel like someone was trialling a finger over her.

The pointer then came to rest in the fine blond pubic hairs, which Rich pointed out "Shows Marketa is a natural blond, although if she had darker hair here would not prove she wasn't, some females have dark pubic hair and blond head hair."

Mr Foster interrupted to say "To allow the class to see the next part we will have to ask Miss Decker to sit on the edge of the table and spread her legs wide. Would you be willing to do that Miss Decker?"

Marketa opened and shut her mouth trying to decide whether to say no but Rich chipped in saying "Come on Marketa, its educational and no-one will think less of you for it."

Mr Foster held up a hand to say stop, "Mr Olivey, please do not try to coerce Miss Decker to do this, it is entirely her choice, and we should allow her to decide by her self."

When Mr Foster stopped talking Marketa said "I'll do it." And jumping down from the table sat on the edge of the table and spread her legs wide, being a cheerleader she could almost do the splits so holding her legs in this position was reasonably comfortable.

At this point Mr Foster, remembering the details he had heard, realised it was time to find another quote volunteer unquote. Looking at the class the most obvious inexperienced boy looking with an obvious crush on Marketa was Michael Stevenson, known by almost everyone in the school as the "computer nerd".

Mr Foster said to Rich "I think its time we brought in another demonstrator so that you can concentrate on the detail while the other holds the relevant items exposed for view as the next parts are relatively small."

Turning to the class he said, "Right which of the gentlemen will volunteer to assist Mr Olivey at this point." Nearly all the boys' hands shot up immediately, but Mike, who was sitting near the back of the classroom, was one that obviously wanted to but was too shy to do so.

Mr Foster said "Right, it seems most of you are a bit too eager, and we don't want any unnecessary over enthusiasm to spoil what has so far been a successful lesson, so I'll choose Mr Stevenson as he is reluctant so is less likely to get carried away."

"Mr Stevenson, would you help us please, and to make if fair on our other two demonstrators, please remove your clothes as well."

Mike rose, a mixture of shock and panic on his face, but the chance to get closer to Marketa too much of an incentive to allow either to stop him. He stripped off his t-shirt, shoes and socks before even thinking about what was to happen, then realising what it meant, he would be naked in front of all the class, stopped undressing. Mr Foster said "Please hurry Mr Stevenson, we need to get on!"

The sudden command triggered Mike to complete stripping and start moving to the front of the classroom, his cock already hard from just thinking of being next to Marketa. As he passed several of the girls sitting at the desks in front of where he was sitting, they all got a good close-up as his cock was just at eye height; Mike was in too much shock to notice.

Rich looked at Marketa and said "Marketa you will have to lay back a bit more to bring your pussy up to the front."

Marketa swallowed hard it would make her even more exposed, but she reasoned, I agreed to do it so here goes." Marketa move to lie back on the table so that the area from her pubic mound to her anus was facing the class, which brought her pussy into the centre of view. As she was feeling somewhat humiliated by the exposure she showed no sign of arousal and her pussy remained closed over.

Mr Foster said to Mike, "Please spread her lips gently so the class can see the inner folds; I suggest you do it with your right hand from below so that everyone can see."

Mike hesitantly put his fingers on Marketa's body, making her jump at the intimate contact, and spread the lips, staring totally fixated on the sight before him. He thought even if I never get this close again I will NEVER forget this.

Rich looked at Marketa's pussy and then turned to the class saying "As you can see, at the moment Marketa is so surprised with the situation she is hardly aroused at all. Mike, can you rub her clitoris, which should cause her to be aroused quickly."

Mike put his left forefinger on Marketa's mound just above the slit, Marketa, realising he had no idea where it needed to be reached over and moved his finger over her clit. After only a few seconds, the combination of the finger lightly rubbing on it and the erotic feeling building in Marketa as she realised where all the boys in the class were looking, raised her level of arousal rapidly. The lips of her pussy filled with blood as she became more worked up and the inner lips opened like an unfolding flower to show the entrance to her vagina.

Rich pointed to the entrance saying, "Now that Marketa is aroused she is ready for intercourse and, as you can see, her vagina has opened to allow the entrance of the penis."

A voice from the back of the class shouted out "No we can't, it's too far away."

Mr Foster tells Mike to keep on rubbing Marketa's clit gently to maintain arousal while the class come forward for closer look one row at a time. Realising it would be less interest to the girls decided to let them have a close-up look at Rich instead. He tells the boys to queue near to Marketa to have a close look and the girls by Rich.

The first boy leans in close enough for Marketa to feel his breath on her, by now very sensitive, pussy. He reaches out with finger to feel it, and finding his finger covered with fluid, sniffs it. Mr Foster tells all boys to try it but be careful and gentle so as not to hurt Marketa, and once they have got the odour to taste it as well. He tells Mike "Keep gently rubbing Miss Decker's clit to maintain the flow but be careful not to over stimulate her, whenever she becomes too aroused paused for a short time to allow her to relax a bit."

Marketa's body was twitching and her head was rolling from side to side with the sensations being constantly created by Mike's gentle ministrations. She was whimpering and saying "Yes yes yes, don't stop, please don't stop" over and over again.

As each of the boys leaned down to look closely a number of them blow a puff of breath, some intentionally, some in surprise, onto to her pussy lips causing Marketa to jump each time at the sudden increase in gentle sensation.

Most of the boys were inexperienced and only rubbed the outer lips of Marketa's pussy, but the others inserted a finger into the entrance and rubbed on the surface inside. Each time a new finger touched her Marketa would buck up and she would gasp or make a squeaking noise. It made it very difficult for Mike to keep her pussy lips open and to only rub gently on her clit, after the first couple of tries he found that keeping the heel of his left hand resting on Marketa's pubic mound he could move with her without changing the pressure.

Mr Foster told the girls to each feel Rich cock, which was hard again but after the previous climax will stand a lot of rubbing before climaxing again. He said "As you will all see Rich also produces some fluid from his penis when aroused. There is much less of this but there should be enough seeping out for all of you to get the odour and a taste."

Seeing some of the girls looking as if he was asking them to do something distasteful he said "Remember everyone, the secretions we are sniffing and tasting in this are perfectly normal and are produced by the body to arouse and aid in sex, there is nothing wrong or sinful in either."

Rich stared into space, concentrating on the diagrams on the rear wall of the room and not on the sensations from his cock, to try and delay the inevitable eruption.

It took over 15 minutes for all the class take their turn to see close-up and get the odour and taste, the class was about evenly split between boys and girls so both Rich and Marketa had a similar number of events to contend with making it difficult not to explode in a climax before all had their turn.

Marketa was in an almost continuous near orgasm due to Mike's gentle rubbing and the fingering by the rest of the boys, and Rich finally lost the fight to not cum while being felt by the last girl, shouting "look out I can't stop it", as she took hold of his cock. Fortunately the girl was standing just to the side so most of the ejaculation went passed her, shooting almost two feet from Rich, but some landed on her sleeve and some on her hand.

The last boy having looked, felt and tasted, Mr Foster told Mike to help Marketa up. He moved so she can bring her legs together and then helped her sit up, she was still having spasms from the extended near orgasm and almost fell against him and he gently wrapped his arms around her to hold her while they subsided. Mr Foster said "Mr Stevenson, don't forget to get the odour and taste yourself."

Mike in a rush, quickly put his hand down and pushed it into Marketa's slit, which caused him to rub her clit harder than expected due to the angle, which pushed her arousal over the top and triggered a massive climax. Marketa's legs clamped down on his hand; trapping it inside her while she exploded in wave after wave of climax. Mike just tried to keep her safe with his free arm and make sure she did not fall off the table edge where they were sitting.

As she returned to coherence she realises she is being held in an embrace from one arm and had another trapped between here legs and looked up to see Mike. "What did you do to me? I've never felt anything like that before."

Mike just said, "Your amazing", then he lent down to kiss her cheek, but she turned her head in surprise and their lips met, hers quickly becoming intense, his initially in surprise but soon returning the intensity.

Mr Foster looked at all three and said would two of you be willing to do the last demonstration for the day and show the actual sex act. Rich said he was totally gone but Mike should be able. Mike was shocked and about to say no when he looked at Marketa to see her reaction and she said "Please, I want you now, I NEED YOU now."

Mr Foster told Rich he should still do the commentary and point out the salient features of what was happening.

Mike whispered to Marketa "I haven't done this before; I don't know what to do." She replied "You hadn't kept a girl in constant orgasm for fifteen minutes before but got it just right, just go with the flow it will be perfect."

Mr Foster told Marketa to lay down on the table and for Mike to climb over her, he then told Rich "Please continue but take them through it slowly so that the various stages can be clearly seen."

Rich turned to the class and said "As you can see Mike is fully aroused, Mike please rise up so we can all see the way your arousal has positioned your penis in the correct position for intercourse."