Author Archives: LEM

Practice, Experience, Learn!

I’ve heard people say “I wish I knew then what I know now”. The statement points to the fact that we are constantly gaining new knowledge and skills. This doesn’t just happen in school of course.

Students often say (and think) that the set work is too hard. But I tell them that whenever people first try to to do something, they might not be that good at it. However, through practice they get better. We learn as we go.
Recently we had a tree cut down in our front yard and we decided to keep the wood for our fireplace. The tree fellers left the wood in roundish pieces which I could chop up.
The last time I chopped up wood, I used an axe but the axe kept getting stuck. Someone mentioned that I should use a block splitter, which is like an axe but with a wide blade that pushes the wood apart as it moves downwards.
So I bought one and WOW! It works so much better. If only I knew then what I know now!
I have also discovered over the past week that bringing the block splitter down between the rings of the tree works better than trying to cut across the rings.
I’m obviously not an expert wood chopper but it’s amazing how often I do something for the first time and I don’t do it very well, but then I get better through practice or learn some new trick that makes it easier. It really gives me confidence whenever I try anything new. I don’t have be brilliant at it, but I’ll improve.

Generalizations about Men and Women Are Fine, but…

It doesn’t happen all that often, but whenever the issue of the differences between men and women comes up in class this is what I give as my opinion.
There is nothing that you can say about the personalities of men that applies to all men and that doesn’t also apply to some or even many women. Likewise, there is nothing that you can say about the personalities of women that applies to all women and that doesn’t also apply to some or even many men.
The physical differences between men and women are obvious. Men, on average, are bigger, stronger, and faster than women, and of course there are the clear differences in their reproductive systems.
However, though we often read generalizations about what men and women are like and how they are different, when it comes to interests, attitudes, and behaviours, there’s a huge overlap.
So, if you want to pursue a career in a field that in the past (or even now) was (or is) more common for members of the opposite sex to get into, then go for it. Don’t let what others like, dictate what you do!
There are currently far more women than men who are primary school teachers, but, boys, if the job interests you, do it. There are currently far more men than women in the computer sciences, but, girls, if the job interests you, do it.
Over the past three decades I have taught literally thousands of students, and, when it comes to brain power, there’s no obvious difference to me between boys and girls. I think there are personality differences between most boys and most girls, but each individual in this room is not “most boys” or “most girls”. You are unique with your own unique interests! So while you’re at school, learn as much as you can to get to where you want to get to.
Anyway, let’s get back to the topic of… (and then we get back to whatever Science topic we were doing)

Best Greek Pita Recipe – Tiropita – Yummy Cheese Pie with Homemade Filo Pastry.

In the animal kingdom, the vast majority of species are born or hatch (or whatever) with pretty much all of the programming that they need to survive. Lizards, turtles, frogs, insects, and fish, for example, never “meet” their parents but they just know how to find food, how to find a mate (when their reproductive systems mature), and how to escape predators (although most of course are not successful at avoiding predators). Birds are not taught how to build nests. They just know somehow.
Mammals, on the other hand, learn quite a lot from their mums and dads. Young bears, for example, learn to hunt by watching their mums hunt. Primates “teach” quite a lot of stuff to their offspring.
Humans, though, learn vast quantities of things from their mums and dads, and also from their relatives, their teachers, and from video, pictorial, and text resources. But just because we are taught something, doesn’t mean that we are immediately good at it!
My mum’s been making Greek pita for decades and is very good at it. I got her to show me how she does it, and though she is 84, she made it look easy. I then tried to make a pita and though it eventually worked out, I found it difficult to make. However, since my first attempt, I have definitely improved.
So kids (and adults), don’t worry if, when you are taught something by your teacher, you don’t understand it immediately. Practice it and you will get better!!

Best Greek Pita Recipe – Tiropita – Yummy Cheese Pie with Filo Pastry

Spiro’s first Greek Pita, a yummy tiropita with homemade filo pastry.

So many things went wrong, but it was worth the effort. So is all of the education we receive both at school and in life!!

This photo shows my efforts on my sixth pita. It looks a lot like my mum’s does!

Live in Lockdown – Cool World 12/09

This may be the first public live musical performance in Melbourne since lockdowns began in March. It was just me practicing the guitar for half an hour in front of a bunch of randoms at Bald Hill Park in Clarinda, which is across the road from my house!
I’m not much of a guitarist and I’m even less of a singer but I got a few claps, so I was pretty happy.
Victoria has the harshest lockdown measures in the world at the moment. However, as a PE teacher, can I encourage all of you to get out and do your 1 hour of exercise. If you live anywhere near Bald Hill Park, come and do some exercise there!
Cool World was written by Australian rock legend Ross Wilson who performed at the school that I work at last year.
Listen to the original (and the best) at

Me versus I

This one simple grammatical rule is not being taught in schools but it needs to be because “me” is not a dirty word!

Let me begin with a poem.

When do we use the word I

And when do we use the word me?

When do we use the word us

And when do we use the word we?

Let me tell thee!

For some reason, younger kids say things like “me and Georgina were playing outside but then it started raining”. Their teachers and parents correct them and say “you’re supposed to say ‘Georgina and I were playing outside…’”.

However, we never then follow up by telling them when they should use the word “me”.

The word “I” is used when the person being referred to is the subject of the sentence. The word “me” is used when the person is the object of the sentence.


On the first day I went to the shop.

On the second day Georgina and I both went to the shop.

On the third day, we both went to the shop again.

Very few people get this wrong.


On the first day, the shopkeeper told me about his new car.

No-one gets this wrong either; “me” is the obvious pronoun.  A lot of people get the next bit wrong, though.)

On the second day, the shopkeeper told … Georgina and me about his new boat.

Way too many people incorrectly say “the shopkeeper told Georgina and I about his new boat”. Why should the inclusion of Georgina change the pronoun from “me” to “I”? It shouldn’t. On the first day, the shopkeeper told me something and on the second day, the shopkeeper told Georgina and me something!

We get it wrong because our teachers told us (correctly) to say Georgina and I (did something), but leave out the equally important correct use of the word “me”, leaving us, from a young age with a fear of the word me.

By the way,

On the third day, the shopkeeper spoke to us again about his new boat.

I and we go together, while me and us go together.

So, if you would normally use the word I in a sentence but there is someone with you, say Georgina and I.

If you would normally use the word me in a sentence, but there is someone with you, say Georgina and me.

Georgina and I went to the shop for a spot of afternoon tea.

When we had finished, the owner approached and spoke with Georgina and me.

Now not only are people, including teachers (!), too afraid to say “Mrs Havisham has approached Mrs Copperfield and me to offer us a pay rise for our exceptional use of pronouns…”, but they don’t even use “me” when they are talking about themselves!

I’ve heard teachers say “If you have any questions, please come and talk to Mrs Liacos or myself and one of us will help you out”.

I can talk to myself and you can talk to yourself, but you can’t talk to myself and I can’t talk to yourself. I can talk to myself and to you, and you can talk to yourself and to me. And you certainly can’t talk to myself any more than you can talk to I! You can, however, talk to me (or to Georgina and me) if you want to.

So that’s all me have to say, oops, I have to say. Don’t be afraid of me. Feel free to use me. And feel free to use the Shedding Light programs which Georgina and I created. If you have any questions, please contact Georgina or me!

230,000 people die in Australia every year. So why the fuss over coronavirus? Here’s why.

I’ve heard people question why so many restrictions have been put in place to combat coronavirus (Covid-19) even though it hasn’t killed that many people. This is a major reason why.

Just over 100 people have died in Australia because of coronavirus (Covid-19). Every single case represents a human being and the pain and suffering for the people who contracted the disease and their loved ones is very real.

However, it is also true, as you can see in the table below, that many more people die from other causes. Why aren’t we forcing people to exercise every day to prevent heart disease? Why aren’t we banning sugary drinks to prevent heart disease and diabetes? Why aren’t we banning smoking to prevent lung cancers and other problems? Why aren’t we banning cars, given that our road toll is about 1,200 every year? (The road toll doesn’t even make the top 20, let alone the top ten.)

So why have we upset so many aspects of our lives and of the economy to fight coronavirus? Well, this is my take (below the table).

Cause of death in Australia (in 2018)



Median Age (years)

(basically, death of baby inside womb due to natural causes)
approx 100,000


(basically, the baby, the placenta, and the amniotic fluid are sucked out of the womb with a mini vacuum cleaner in a procedure called vacuum aspiration)
approx 70,000


Ischaemic heart diseases
(basically, heart attacks; the heart doesn’t get enough oxygen because the arteries supplying blood become blocked)




Dementia, including Alzheimer disease
(a loss in awareness and an inability to plan, reason, hold complex thoughts etc.)




Cerebrovascular diseases
(basically, strokes: the brain doesn’t get enough oxygen because the arteries become blocked or they burst)




Malignant neoplasm of trachea, bronchus and lung
(basically, cancer of the respiratory system; abnormal growths of tissue that interfere with normal functioning)




Chronic lower respiratory diseases
(basically, lung damage; causes include tobacco smoke and other toxins, pollution…)




Malignant neoplasm of colon, sigmoid, rectum and anus
(basically, cancer of the intestines; abnormal growths of tissue that interfere with normal functioning)




(basically an inability to regulate blood sugars effectively)




Malignant neoplasms of lymphoid, haematopoietic and related tissue
(basically, cancer of bone marrow, the blood, lymph, and lymphatic system)




I believe that it comes down to the fact that no government (state or federal), can be blamed for most causes of death, but if any government did nothing about coronavirus and fatalities were higher in that territory than other territories, then they could be blamed directly. If, for example, Victoria had done nothing about coronavirus while NSW had lock downs, and Victoria’s coronavirus death toll was 500 and NSW’s was only 50, then the extra deaths in Victoria could (and would) be seen as the Victorian government’s fault.

Therefore, generally, no government really wanted to do anything hugely different to any other government because they didn’t want to be blamed. You can’t blame any government for the road death toll because cars have been around for a century. You can’t blame any government for heart disease, because heart disease has been around for, well, who knows how long? As long as seat belt laws and speed limits are put in place and there’s a bit of research funding given to scientists trying to reduce the impact of heart disease and cancer, governments can’t be blamed for most deaths.

(Whether abortion, the number 2 cause of death in Australia every year, fits neatly into my theory above is debatable. Many people do blame governments for allowing this huge loss of life to occur.)

Now I don’t mean to be cynical. I am definitely not saying that governments don’t care about people and that they only care about votes. I genuinely believe that they (individual members of governments) would actually blame themselves if more people had died because of inaction.

Weighing up the the value of the economy vs the value of human lives is something that governments do all the time. But if a government hadn’t done anything about coronavirus and more people had died in one territory compared to other territories, the people in that territory would have blamed that government and most government members themselves would have felt responsible on a deeply personal level.

So, maybe they went too hard on the lock downs and maybe they didn’t. Being in government must be very difficult! A lot of it was educated guess work and it’s probably true that the federal government’s initial decision to stop people coming into Australia from China was the biggest factor that kept us relatively safe from this new virus. So far.

Anyway, I’ve gotta get out and do some heart-disease-destroying, diabetes-diminishing, cancer-reducing exercise. Before the government imposes it on me for my own good.


Figures in the table above come from

Abort 73,
the Parliament of Australia website,
The Australian Bureau of Statistics. Their figures do not include deaths prior to birth and they break up cancers into different types. If all cancers were counted together, cancer would probably rate as number 3 on the list above.

Married Half My Life Day

Romantic Maths.
Numbers are important! Today marks the special day in my life where I have now been married to my beautiful wife for as long as I had been unmarried. From tomorrow, I will have had more experience in life as a married man as I had had as a single man.
The calculation is pretty easy. To calculate your own “Married Half My Life” Day just follow the instructions in the video below.
It’s good being married. Studies have shown that married people are healthier and happier and that they live longer than single people. I don’t know if it’s true or not or whether, if it is in fact true, that it’s a chicken and egg situation; maybe people who are chronically unhappy and unhealthy find it harder to find a partner. We always have to be careful when we’re interpreting data.
Generalizations are fine, but they say nothing about individual cases. In my case though, it’s fantastic being married to Georgina, my wife and fellow video producer.

The Most Important Law that Students Should Be Taught

Good morning, everyone.
Before we begin the lesson, let me tell you about what I call the First Law of Economics.
This is it:
If you want someone to give you something, you have to give them something in return of a perceived equal value.
This Law applies to individuals, to businesses, and to entire countries.
So, if you go to the shop and you want to buy a T-shirt, they will give you a T-shirt, but they expect you to give them something in return: in this case, money. We can call the First Law of Economics the Law of Mutually Beneficial Exchange.
When, in the future, you get a job, what’s really happening is that you are going to give your time and your skills to the person you are working for and that person, in return, will pay you. Many of you will work for a boss, and so the exchange of skills (and time) for payment will be made through the business you work for. Some of you may start a business though, in which case you might be dealing directly with customers. When, for example, your tap is broken, you might call a plumber and the plumber comes and fixes it. In exchange for the plumber’s time and skill, you give the plumber money.
Basically business and individuals provide what are called “goods” (physical things like a chair or a light globe) and “services”. A service is something like the work that an accountant does when he or she prepares your tax return for you. Mechanics offer goods (like motor oil or spark plugs for your engine) and services (the actual work they do to fix or service your car). These goods and services are often referred to as “parts and labour”.
So, if in the future you want to work, it’s not really a matter of just saying you want to find a job (although there’s nothing wrong with that expression). It’s really a matter of mutually beneficial exchange. You will provide your skills or products or time or services to someone else and that someone else will give you payment in return.
Now, a lot of you may never have thought about it this way. Up until now, nearly everything you have has been provided for you. Your parents provide food and clothing and stuff and they don’t really ask for much in return. Love of course complicates things. (As a parent myself, the “payment” I receive from my own kids is the gratitude they express to me and, let’s face it, when they do well, I feel good! As I said, love complicates things.) In the real world of work, however, no-one is just going to give you stuff that you want if you don’t provide something in return that they want.
So, why are you at school? It’s because you need to learn the skills that you need to offer future bosses and future customers—for which you will receive your income.
If any of you have little brothers and sisters in primary school, you will know that there is no way they would be able to do most jobs. Most of them would struggle even to make, say, a coffee at a local café, or to stack shelves at the supermarket, both jobs that don’t require a huge amount of training and which don’t pay that well. However, most of you in this class could easily do these jobs because you’re a whole lot smarter than you were in primary school, and you’re bigger and stronger.
But this leads us to an important point. If the only skills you have are also possessed by millions of other people, then why would someone pay you top dollar when it’s easy for a business to find someone else to do the same work for a lower wage. We now get into the Second Law of Economics: Supply and Demand. Put simply, if it’s easy to find someone to do a particular job because it’s a low-skill job, then the payment will be low as well.
The people who are paid the most are the people who provide skills or services or products that few other people can provide. Lots of people can stack shelves at a supermarket, and though it’s a really important job and an honourable job, it’s a low-paying job.
So what skills do you have to offer now and what skills will you have to offer in the future? I want to encourage you all to work hard, to learn as much as you can at school, and to become as good as you can at reading, writing, and mathematics. In the world of work, no-one really owes you anything. To earn an income in the future, you will have to offer something in return. So make sure you gain the skills you need! And of course you’re all going to need the skills that I’ll be teaching you!!
Anyway, let’s begin the lesson.

Note to Teachers:

I often refer back to the First Law of Economics because of its pervasiveness. It doesn’t just apply to individuals but also to whole countries. For example, Shedding Light on Atoms Episode 3: The Discovery of Atoms describes how elements are extracted from mineral ores (for example, iron from iron ore which contains a high concentration of iron oxide). I often pause the video and talk about how Australia receives income from other countries by selling the iron ore and the steel that we produce to other countries.
I might say something like…
A large part of Australia’s wealth is generated from the fact that Australia as a country has things (in this case iron ore) that other countries want and which they are prepared to pay for. The international monetary system is pretty complicated but, at a really simple level, Australia gives iron ore to China and China gives Australia things that it produces (such as electronic equipment). It’s the First Law of Economics at work.
A country can only import things if it exports things as well.
And an individual person can only acquire something if that individual gives something in return. It’s the First Law of Economics: if you want someone to give you something, you have to give them something in return. And what do you have to give? Maybe not much at this stage because you’re young. But you’ll grow and continue to learn and by the time you finish your education you’ll have much much more to give than you do now!

Always do this before you try to answer a question on a worksheet or a test.

I would have thought it was obvious but it wasn’t obvious to (at least) three Year 11 Physics students in a class of about 20.

I had just finished teaching them the Law of Refraction using LEM’s Shedding Light on Refraction program. The bonus feature on this program explains how to calculate the angle that light will refract when it passes from one transparent medium to another. I then gave them the The Law of Refraction Worksheet. The worksheet has a list of formulas and other data. Here is a screen shot of part of the worksheet.

Question 3 asks:
A ray of light travels from air to glycerol at an incident angle of 38° and is refracted at an angle of 24.6°. What is the refractive index of glycerol?

Two students over the span of about two minutes asked the same question which was basically, “Sir, can you help me with this? I don’t know the refractive index of glycerol.”

Neither of them had read the question!!

Just as I was telling the second student that it’s the refractive index of glycerol that they needed to find, I heard another student (a third student) ask the same question to one of his mates.

I’ve been using this worksheet for years now and this had never happened before, but I thought this was a golden opportunity for an important teaching moment and I immediately stopped the whole class.
“Three students have just asked about question 3. They got confused because they didn’t know the refractive index of glycerol. This might sound a little crazy, but before you try to answer a question, you should always READ THE QUESTION first!!!”

A colleague of mine served as a Year 12 examiner for the Year 12 Chemistry exam for many years. A few years ago he told me that students routinely didn’t read the question in full before writing down their answers.
A common mistake was to answer only part of the question when the question was clearly in two parts. Another common mistake was to focus on a particular word in the first sentence of a question and then assume that the question was related to the definition of that word.

So, in summary,
STEP1: Read the Question
STEP 2: Answer the Question.

Never attempt to do it the other way around.

A Much Easier Way

What a teaching round! I recently had to supervise a pre-service teacher (what we used to call a student teacher). This was the last of three rounds that he did with me this year.
Unfortunately, I wasn’t able to let him teach the recommended number of lessons on his previous rounds because of the fact that I only work part time as a teacher. This time, however, I suggested that he teach both of my junior classes: a Year 9 class studying Heat and a Year 10 class studying Chemistry.
This would have been a huge workload because he also had to take a Maths class with his other supervisor.
To make his life easier, I suggested that he use the Shedding Light on Heat series to teach the Heat unit and the Shedding Light on Atoms series to teach the Chem unit.
So, on Day 1, he used Shedding Light on Heat Episode 2: Changes of State and its accompanying worksheet to teach the class why things change state. The explanation side of the teaching was taken care of by the video with animations, actual footage, and explanations. The students then used their memories and the online text book on the Changes of State page to answer the questions.
It was so easy!
I’ve seen plenty of pre-service teachers struggle to explain things verbally while using white-board markers and hand-drawn diagrams. Unfortunately, I’m also guilty of giving students less-than-satisfactory explanations that take too long. 🙁 A short sharp video, though, can take care of the explanations, which frees up a lot of time so that students can get on with actual learning activities.
The pre-service teacher also started teaching my Year 10 class about electron shells using Shedding Light on Atoms Episode 6: Electron Shells. Once again it was so much easier than legacy approaches.
By the end of his round he had taught the Year 10 class about electron shells, covalent bonding, and ionic bonding. During lessons, he would move around the room helping students who needed additional support.
He didn’t use just the Shedding Light programs, though. Interspersed throughout his round he organised a whole lot of pracs and a few mini-assignments. He also regularly asked students to read out their answers to the class, something I always do when I’m teaching to encourage better literacy. See The First Thing I Tell A New Class.
The reason LEM started making the Shedding Light videos was on full display during the teaching round. A good video makes it easy for any teacher, regardless of expertise, to communicate science concepts easily and effectively to their class, especially when the video is accompanied by learning activities and pracs.
The work the students did during the teaching round was of a very high standard. The pre-service teacher regularly collected it and then gave feedback.
Overall, he ended up teaching about twice as many periods as he needed to since the Shedding Light programs helped him in quite a few of them.
So, whether you are a beginner or an old hand experienced, try using a Shedding Light program to teach your class. They are available to schools that have ClickView, Learn360, Films on Demand, and SAFARI Montage, or you can order directly from the LEM website.
I wish the pre-service teacher, and you, dear reader, every success.