IGCSE Human Biology: Reproduction

Revolting post ahead (or so Gary tells me 🙂 I have no filtering… ).  Sensitive constitutions should exit ASAP.  You have been warned.

Learning about reproduction with five teenagers can be humorous, not to mention embarrassing…for them.  I was adamant that I would teach this to them without all the embarrassed giggles one might expect from a topic such as this.  The major problem lay in the fact that said teens just did not or could not believe that my goal was not to embarrass them.  And, sheepishly, I would have to admit that, in general, embarrassing my teens is one of my funnest past times!  But not when it comes to education.  Education is serious, and whilst I absolutely expect it to be fun, this is not the time I will be focusing on teasing my teens and their poor friends (Honest. No really, I promise.).

Last week we learnt about the human reproduction tracts.  I had decided to appeal to their stomachs and maybe also to their sense of the ridiculous and spent a happy hour at the supermarket picking up fruit, veg and sweeties that might help me to make a ‘never-to-be-forgotten’ model of both the male and the female reproductive tracts.

The female’s bits and pieces were relatively painless, and apart from a small grin to myself whilst paying for the items, it was simple to find suitable food for my model.  The male’s I had struggled with, purely on the basis that most of the mechanics resided outside the body and such a model would therefore cause far more embarrassment to the male teens than the female model would to the girl teens.  I can’t tell you how long I spent with a Flump in hand, wondering if it might not be perfect….

In the end I decided, with a wry grin, that tempted as I was, I couldn’t do it to B14 and T14.  T might very well have disowned me.

Introduction to Reproduction 

Following Edexcell’s IGCSE syllabus for Human Biology, I needed to teach the following to my children:

• Structure of the male reproductive system
• Structure of the female reproductive system
• Demonstrate role of hormones in Menstruation
• Fertilisation & methods to improve fertilization
• Methods to prevent fertilization
• Formation of zygote from an ovum, then its development into an embryo

This week we were focusing on the reproductive systems, fertilisation and implantation.

I would be using the Edexcel International GCSE Human Biology Student Book to guide our learning, only we would be focusing on a fuller understanding by building models of everything.

Before doing any hands on stuff, I had spent some time in our morning meetings going through Mitosis and Meiosis; diploid and haploid cells; the formation of gametes in the testes and ovaries and the number of chromosomes each human diploid (46) and haploid (23) cell contained.  I did it until the children were sick of me asking but were entirely word-perfect in their definitions and understanding.

The Female Reproductive Organs

For the first basic model we needed to include V****a, uterus and its lining, Fallopian tubes, Ovaries.  For this I bought a melon, laces and a kiwi.  Half the melon, with the seeds scraped out, became the uterus, with a tiny bit of strawberry jam as its lining; the laces became the Fallopian tubes; the kiwi, cut in half, became the two Ovaries:

We talked about the limitations of such a model and the fact that our model does not show a V****a or the ligaments which hold the ovaries in place.  That said, it was a very useful model to show how fertilisation occurred.

The Male Reproductive Organs

To save the males of the group embarrassment I had them both look these up at home and learn.  However, I did draw a model on our white board for the children to label each day until they had all the structures learnt off by heart:

It could stay up as we could hide it with our curtain, so T wasn’t too unhappy about it….until Lorna came by that evening and on purpose pulled back the curtain so that everyone at the dinner table (y’know, whilst we were eating) could see the male reproductive tract in all its dubious splendor.  I was tempted to get a photo but, honestly, I think my son may have run away and found some parents who were a little more sensitive.  So I didn’t.  Yes, I know, how controlled am I? (I have to admit to mischievous finger syndrome, whereby my fingers sometimes have a mind of their own, itching to post the photo.  But I reined them in).

They also learnt the structure and function of each part of the sperm.

Fertilisation

I used the first model to explain fertilisation.  We used a Tictac as a sperm/zygote; a slice of a marshmallow squashed to make flat as the placenta; a cut lace as the umbilical cord and a pink marshmallow for the baby in an amniotic sac (it was a girl 🙂  ).  We used a thick mess of strawberry jam to illustrate the uterus lining thickening in readiness for the pregnancy:

We learnt that fertilisation occurs when two haploid gametes (sperm and egg) with 23 chromosomes join together to create a diploid zygote with 46 chromosomes.  This occurs most often in the Fallopian tubes.  We discussed the rare complication of a tubal pregnancy whereby implantation occurs in the Fallopian tubes rather than the uterus.  These tubes are not able to carry a viable pregnancy very far and always ends with a tubal abruption which is preceded by violent side pain and excessive bleeding, and is always an emergency.

Most likely, if implantation occurs, it will occur in the uterus, which under the effects of hormones has been preparing for possible implantation by thickening its lining to create the best environmental conditions to grow a baby:

After implantation, a placenta grows, alongside an umbilical cord and an embryo.  The placenta is made from lots of blood vessels.  Its large surface area reflecting the sheer importance of the blood vessels to provide the growing embryo/fetus and baby with sufficient oxygen and nutrition.  The umbilical cord is a continuation of the placenta and is attached to the baby via what will eventually become its belly button:

If implantation does not occur the embryo or unfertilised egg will be removed from the woman’s body, along with the lining of her uterus during her menstruation:

After I had finished embarrassing demonstrating to the teens I asked them to create their own model from a kinder egg, some marsh mallows, tictacs, strawberry jam and strawberry laces.  After they had each explained their model clearly, demonstrating their knowledge on fertilisation, implantation and pregnancy they could eat their uterus.  This they did with enormous alacrity, finishing in super quick time and devouring the lot.  No-one pondered on the fact that they were effectively eating their reproductive organs….

Happy sigh.  The teens were educated, fed and embarrassed.  Could life get any better?

This week we will be studying menstruation and the role of hormones in this and maintaining a pregnancy.