Author: physicsteacher

website: http://www.thephysicsteacher.ie/ Twitter: @physicsteacher youtube: http://youtube.com/yerrahyouknow

Everything a Primary School teacher (or student) needs to know about gravity. And then some.

This post is in the context of a question posed by a primary teacher on a forum recently. Rather than reply there I thought it safer to do so where I could offer a more comprehensive answer.

We tend to associate the concept of gravity with the English scientist Isaac Newton who lived in the seventeenth century.
But he didn’t ‘invent’ gravity; objects were falling to earth long before Newton arrived on the scene, so what exactly did he do?

1.
He did what so many other kids do; he asked asked a silly question. ‘Why do things fall down?’
It does seem like a silly question, which is why nobody took it seriously before, but when you think about it it’s actually quite profound; how does the apple in an appletree ‘know’ which way to fall? How does the earth ‘know’ (if it pulls the apple down) that the apple is there in the first place ? Newton was never able to answer that question. He famously said  “Hypotheses non fingo” (Latin for “I feign [frame] no hypotheses,” or in other words, “I haven’t a clue why this works the way it does”). It’s not like there’s a string connecting the two objects, but yet the apple acts as though there were indeed an invisible string pulling it downwards.
What form does that invisible string take?

I don’t know the answer, but I do know that scientists haven’t fully worked it out yet either.
It has been suggested that all objects exchange particles called ‘gravitons’ and it is as part of this exchange process that the objects come together. The problem is that these gravitons have never been detected.

Another possibility is gravitational waves. These were postulated by Einstein in his Theory of General Relativity. There has been some indirect evidence for these but again they haven’t yet been detected directly. We know we don’t know all there is to know about gravity, and to suggest otherwise would be to do a disservice to your students. In fact the same holds for a lot of science. Gravity does seem to be a little like magnetism, yet the rules which govern gravity don’t work for magnetism and vice versa. The holy grail of physics is to show how the rules that govern the motion of very large objects like planets is connected to the rules that govern the operation of very small objects like atoms. And there’s absolutely no reason why one of your students can’t be the one to make this connection and win their very own Nobel Prize (with a bit of luck they will acknowledge  you  in their acceptance speech as the spark which ignited their passion for Science).
Matthew is a former student of mine and is currently doing a PhD with NASA on this topic. I asked him to explain it to me:

“In the Einsteinian framework, however, gravity is not a force but a curve in space-time. So any object with mass induces a curve in the spacetime around it. Any other object no longer travels along a flat spacetime, but along a curved path. That’s essentially what’s happening to the apple. Instead of hovering at the end of the branch as it would in a flat spacetime, the ‘forward direction’ of spacetime is curved due to the Earth, so the apple just follows that curve, which in three spatial dimensions is just a straight line down.”

Watch the following clip for a wonderful demonstration of a curving space-time –  imagine doing this with your kids in class: you can tell them you are studying Einstein and doing Rocket Science.

But while Newton couldn’t say why gravity worked, he was able to quantify the force of gravity, i.e. he was able to devise a formula which now enables us to say how big the force of attraction will be between any two objects. It depends on how big the objects are (or more specifically their masses) and the distance between them.

It turns out that any two objects will exert a gravitational pull on each other. Now this is mad. It means that there is a force of attraction between you and your biro, and if it was just the two of you floating in space with no other objects or planets in existence, that force of attraction would result in the biro moving towards you and you moving towards the biro. Similarly there is a force of attraction beween each student and the student next to them (cue lots of giggles) and the bigger the size (or mass) of either student, the bigger will be the force.

2.
Newton also established that the force that kept the planets in orbit around the sun was the same force as that which pulled the apple to earth. This idea was a big, big deal at the time. It meant that the planets followed the same laws of physics as objects on earth. Prior to this ‘the heavens’ were thought to be the realm of the gods or God and therefore not subject to our analysis but after Newton they were seen as fair game for anybody to study. I don’t think there’s any way we can really appreciate how big a deal this was. And while Newton wasn’t the very first to realise this, he was the first to demonstrate it mathematically.

The following is a nice video which outlines the significance of Newton and Einstein to our understanding of gravity. You only need the first ten minutes.

The bottom line for me is that you have an incredible audience who will lap this stuff up. Please, please don’t play down the mystery or the wonder. That, unfortunately, is what happens at second level and I have been trying to get teachers to fight it my entire professional career, with very limited success (it doesn’t seem to bother many other teachers, but I have it bad).

Don’t allow your lack of technical knowledge to put you off engaging with the material. Remember when it comes to Science nobody, and I mean nobody, has all the answers. If we’re looking to turn some of these kids into scientists then what they need more than anything else is curiosity and a good old-fashioned sense of wonder. If you can help develop that then everything else will follow.

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Fun (and very effective) revision activity

Here’s an oldie but a goodie (I first did this as a Fifth Year student in Tarbert Comprehensive on a religious retreat back in Ballyheigue. It’s also all I remember from the retreat). It is an exercise in communication but acts as both an excellent revision activity and ticks the verbal literacy box. And it’s a lot of fun.

I did it with my Leaving Cert Physics class because I have them last class on Friday (and Jacqui finds it hard to concentrate). So a challenge I have now set for myself is to find a fun learning activity for them every Friday between now and May.

photo(1)
Students pair up in twos (I love saying that, just to annoy the pedants). They can pair up in threes if there’s one left over.
Students sit back to back.

There are 24 mandatory leaving cert experiments. The first student (student 1) picks an experiment (or is assigned one) and, with his (or her) back to student 2, proceeds to instruct on how to draw the experimental apparatus. But here’s the kick: student 1 can only instruct student 2 one line at a time, e.g. “Start at the top of the page and draw a line parallel to the top half-way across. Now draw a line down three quarters of the page”. Student 1 cannot however tell student 2 to draw a power supply; student 2 has to figure this out from the instructions. Obviously student 2 doesn’t know what the experiment is and the aim is for him or her to figure this out in the shortest time possible. Neither can student 2 communicate with student 1 in any way; he just has to follow instructions as best he can. At the same time student 1 can’t look over her shoulder to see how the diagram is progressing.

Once identified, student 2 then gets a turn at calling out the instructions for another experiment which student 1 has to draw and try to identify in a shorter time.
Alternatively have all pairs doing doing the same experiment and see which pair can identify the experiment first.

So yes it’s great fun, and yes it really demands a high level of verbal and spatial reasoning, but the reason I really like it is because it involves active learning; student 2 is mentally retrieving all the experiments to see which one best matches the diagram. And this has been shown, time and time again, to be one of the most effective ways to learn.

You could spend five minutes on this at the beginning of every lesson. There’s also no reason why this can’t be rolled out for Junior Cert Science students.

Another nice aspect to it is that there is no preparation on the teacher’s part; no photocopying, correcting or cleaning up afterwards.

Finally, we use mini-whiteboards (also known as “Show Me” boards) in class – they are perfect for this activity.

Imagine if we all shared our own one favorite fail-safe activity?

Misconceptions about how students learn

Otherwise known as “How to study hard and still fail”

We’ve all come across the student who works hard in class and puts in the hours at night doing homework but never quite does well in class tests. Or perhaps it’s the student who does ok in class tests but then bombs the end-of-term exam and can’t understand why. The following may help in this regard.

Rate the following study techniques on a scale of 1 – 5 for effectiveness (5 being the most effective)

1.      Highlighting important material

2.      Writing out notes from a textbook or copying from teachers’ notes

3.      Reading over material covered in class

4.      Testing yourself

5.      Looking at mindmaps

6.      Creating mindmaps

7.      Making flashcards

8.      Testing yourself using flashcards

9.      Cramming the night before the exam

We’ll come back to these in a minute, but in the meantime here’s another task for you:

You have a Science test on Friday.
You have given yourself two hours to prepare for this over the course of the week, consisting of a half hour on Monday, Tuesday, Wednesday and Thursday night.
Which of the following four options is the most effective and which is the least (try it yourself before looking for the answer)?

Study  Study  Study  Study

Study  Study  Study  Test

Study  Study  Test     Test

Study  Test     Test     Test

The key to how the brain remembers information is retrieval. The more times it has to retrieve certain information, the more it ‘realises’ that this information must be important and therefore it stores it more securely (think of it as the brain’s hard-drive).

Care to re-evaluate your answers to the tasks above?

For study techniques the most effective option is testing yourself.
This is not only so that you can check your answers to see what you got wrong, but also (and this is the bit most people don’t realise) because the mere act of retrieving the information results in that information being stored more securely from then on.

What about highlighting important material?
You might as well be watching the Simpsons

What about reading over your notes (and your teacher may even have told you to do this for homework)?
You might as well be watching the Simpsons

Making flashcards?
You might as well be watching the Simpsons

Using flashcards?
Here you are testing yourself in a way that requires retrieval of information, so yes – very effective.

Mindmaps?
Interestingly, the research here shows that using mindmaps is relatively ineffective (no retrieval) but making them in the first place can be beneficial once you’re not merely copying it from elsewhere. If you have to think about how various concepts are related then the brain is constantly retrieving information, but once it’s done then it is of little further use. It may however help another student see the connections if he cannot make them for himself. So reading somebody else’s mindmaps may be a useful starting point on the journey of learning, but it’s not much more than that.

Writing out notes
Lots of students like to do this but unfortunately – you’ve guessed it; you might as well be watching the Simpsons.

 

I may be guilty of exaggerating slightly for effect and there may be contexts where some of these techniques are more useful than I’m suggesting here, but it’s only to emphasise the main point; students (and teachers) labour under some serious misconceptions when it comes to study.

So all study techniques are not equal.

And just because Moira is spending three hours up in her room every night ‘studying’ does not mean that this will automatically translate into good grades. It may also explain why her friend Jane, who only spends one hour a night studying, can outperform her when it comes to exams.

You have been warned.

A few points which we left dangling:

  • Why aren’t students aware of this?
  • To what extent are teachers aware of this, and if not why not?
  • How can we get students to change their study techniques?
  • What can teachers do to encourage students to change how they study at home?
  • What can teachers do in class to incorporate these ideas?
  • Why is it so hard for teachers to change their teaching styles to adapt to new ideas?

For another day.

Also for another day: how effective is cramming?

Finally, back to Friday’s Science test.
Most students go with option one.
Option 4 is the correct answer.

This is the second in a series of blogposts to accompany the new website betterteaching.ie. Over time, every webpage on the site will have an introductory post at the top. This post acts as an introduction to the Student Learning page. The various ideas above have been sourced from the posts on that page, in particular the work of Daniel Willingham is worth reading. It will take time to browse through all the information, so it may be worthwhile to bookmark the page and come back to it when free.

The following is one of a series of videos which discusses various study strategies, and in particular the importance of ‘deep processing’ when learning material or as the speaker says; how to study hard and still fail.

Does the world really need another education website?

index

Why create betterteaching.ie?

I am halfway through my teaching career (once outside interference is kept to a minimum) and when I look back on my time as a teacher I want to know that I was the best that I could be. I could use students’ exam results as the benchmark for this, or maybe rely on my own gut feeling, but that, tempting though it may be, would be highly questionable.

So I look for a more objective basis. How do I know I’m a good teacher? What are the qualities of a good teacher?  Is it even possible to be objective about such things?

 

The answer, it turns out, is none too flattering.

 

I believe there to be a good atmosphere in most of my classes, and yes the results are good and yes the students think I’m doing a stand-up job thank you very much. But if I take a look at what is recommended best practice elsewhere it turns out that I am ticking very few of the required boxes. In fact I am a perfect example of the type of teacher that fools just about everyone. The biggest black mark against my teaching is, ironically, that I teach too much. I spend too much time talking, too much time demonstrating and too much time entertaining. But there’s no time left over for standing to one side and allowing (facilitating) the students to learn from each other – a process which has been shown time and time again to be a much more effective learning technique.

You see with me the focus is on the teaching; I am the sage-on-stage and all eyes are on me at all times (or at least they should be). But the focus shouldn’t be on the teaching, it should be on the learning. And for that to happen effectively I need to move to one side, away from the spotlight, and act as a facilitator. But it is really, really difficult to change habits of a lifetime.

So where do I go to find best practice?  Short answer: Online.
Twitter has a poor reputation in many quarters because it is seen as little more than a time-wasting program where we can read the online diaries of the rich and famous.

But it has another side. Many of the best teachers, educators and educationalists are on Twitter and use it to share their ideas and resources. By following them I can become more effective at spotting what’s right and what’s wrong with my own teaching and do so at a pace that suits me without anybody else judging me. The same goes for blogs. And that’s mostly what this website is built around. Simple as.

So what are the issues I should be familiar with?

Well they’re all on the homepage, with the key ideas highlighted (see above).

There are a lot of other teachers out there who, like me, teach in a traditional manner; a format which probably hasn’t changed much from the time of Socrates. It’s not just that this is considered to be ineffective, it’s that much more productive alternatives have been developed, particular in the last couple of decades as a result of advances in neurobiology, cognitive science and psychology (yet another reason to love psychology). One of the key areas is in how we assess our students.
Anybody reading this blog or webpage is already familiar with the phrase ‘Assessment for Learning’, but there are a lot of us out there who aren’t.

Some other key ideas in education which merit having their own page above

  • The importance of reflecting on your work
  • How to engage in Continuous Professional Development (CPD)
  • How to develop a Personal Learning Network (PLN)
  • The importance of failure as a key step in the learning process
  • The idea that praising a student for excellent work can be counter-productive (we should be praising the effort put in instead)
  • The importance of a student’s (and a teacher’s) mindset in the classroom
  • How to use technology effectively
  • How to set homework effectively
  • How to engage with parents so that they become an integral part of the learning process
  • How to know that your students are learning (and that what they’re learning is what they’re supposed to be learning)
  • How to build a student’s resilience
  • How to question students effectively
  • What resources should I have in my classroom to help me?
  • What role does school leadership play in your teaching?

And what about the one issue many of us never talk about publicly, while privately it can be the cause of more stress than everything else put together: class discipline? Believing that to even speak about it is a sign of weakness means that it’s going to be a lot harder for us to find out how to improve it in our own classrooms. Here at least you can find out about the experiences of others and read about what worked (and just as importantly what didn’t work) for colleagues.

Or how about how students actually learn best? Do you know what the best practices are? Do your students? More importantly are you and your students aware of the study techniques that students spend most of their time on but which are quite ineffective?

I believe there is a ethical and indeed moral obligation on all of us to be the best we can be in whatever field we work in. For me this website represents  a step on that journey.

This is the first of a series of blogposts to accompany the website. Over time, every webpage on the site will have an introductory post at the top.
The design is deliberately minimalist. In a world where style rules over content this is my tilt at the windmill.

about this site

Let the adventure begin.

Just so you know, nobody knows what energy is

The following acts as my introduction to the students’ notes on the Energy chapter.

What is energy?

Nobody knows what energy actually is and by pretending otherwise we actually do you the student a disservice. Not only are we ignoring the wonder associated with the idea, we are also denying you the opportunity to engage with the concept at any level beyond the superficial.

Bottom line; nobody gets energy because there’s nothing to get. Energy is not tangible (it is ‘an indirectly observed quantity’); you can’t hold it in your hand, you can’t weigh it on an electronic balance, you can’t see it, touch it, smell it etc. Yet when the universe was first created there was a certain amount of this put in to the mix (actually now that I think about it the mix itself was energy (with perhaps just a little dash of time)), and it’s all still there today. Its form can change, but the energy itself can’t ever disappear – no sirree bob.

It could be argued that it is in fact merely an accountant’s trick which enables him to ensure that all actions balance.

Consider the following analogy which I like to use.

If a child asks you ‘what is money?’ you could take a few coins out of your pocket and show them to the child and say ‘this in money’. Now fast forward a couple of decades; all transactions are now done electronically/online and all coins and paper money are no longer legal tender. Now how do you explain what money is?

Well it’s a means of payment for goods and services, right? Somebody sells you an orange and you agree to transfer into their account a set amount of this ‘money’. And now that the shopkeeper has this money in his account he can use it to buy something else. So in effect money is just a transferrable IOU.

Now energy is a bit like this, but there is only a certain amount of IOU’s in the universe and this was set when the universe first came into being.

To complicate matters further, since the early part of the last century we now know (thank you Albert) that all matter (‘stuff’) is basically energy in another form.

Anyone still with me?

 

All right, let’s listen to Richard Feynman give his take on it.

There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call “energy,” that does not change in the manifold changes that nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says there is a numerical quantity which does not change when something happens . . . it is a strange fact that when we calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same. It is important to realize that in physics today, we have no knowledge of what energy “is.” We do not have a picture that energy comes in little blobs of a definite amount. It is not that way. It . . . does not tell us the mechanism or the reason for the various formulas.

The Feynman Lectures on Physics Vol I, p 4-1

When Feynman wrote,
“It is important to realize that in physics today, we have no knowledge of what energy is,” he was recognizing that although we have expressions for various forms of energy (kinetic, heat, electrical, light, sound etc) we seem to have no idea of what the all-encompassing notion of “energy” is.

The various forms of energy (½mv2, mgh, ½kx2, qV,mcT, ½I2, ½CV2, etc.) are abstractions not directly observable.

2007 American Association of Physics Teachers

Now with that interesting bit out of the way, let’s go see what we need to know for the exam.

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CERN announces discovery of new element: Governmentium

Researchers at CERN have this morning announced the discovery of the heaviest element yet known to science. The new element, Governmentium (symbol=Gv), has one neutron, 25 assistant neutrons, 88 deputy neutrons and 198 assistant deputy neutrons, giving it an atomic mass of 312.


These 312 particles are held together by forces called morons, which are surrounded by vast quantities of lepton-like particles called pillocks. Since Governmentium has no electrons, it is inert. However, it can be detected, because it impedes every reaction with which it comes into contact.

A tiny amount of Governmentium can cause a reaction that would normally take less than a second, to take from 4 days to 4 years to complete. Governmentium has a normal half-life of 2 to 6 years. It does not decay, but instead undergoes a reorganization in which a portion of the assistant neutrons and deputy neutrons exchange places.

In fact, Governmentium’s mass will actually increase over time, since each reorganization will cause more morons to become neutrons, forming isodopes. This characteristic of moron promotion leads some scientists to believe that Governmentium is formed whenever morons reach a critical concentration. This hypothetical quantity is referred to as a critical morass. When catalysed with money, Governmentium becomes Administratium (symbol=Ad), an element that radiates just as much energy as Governmentium, since it has half as many pillocks but twice as many morons.

“Of all the parts of a school curriculum Religious Instruction is by far the most important . . .”

Rules for National Schools

Rule 68

“Of all the parts of a school curriculum Religious Instruction is by far the most important, as its subject-matter, God’s honour and service, includes the proper use of all man’s faculties, and affords the most powerful inducements to their proper use. Religious Instruction is, therefore, a fundamental part of the school course, and a religious spirit should inform and vivify the whole work of the school.

The teacher should constantly inculcate the practice of charity, justice, truth, purity, patience, temperance, obedience to lawful authority, and all the other moral virtues. In this way he will fulfil the primary duty of an educator, the moulding to perfect form of his pupils’ character, habituating them to observe, in their relations with God and with their neighbour, the laws which God, both directly through the dictates of natural reason and through Revelation, and indirectly through the ordinance of lawful authority, imposes on mankind.”

See the full set of rules here.
Apparently these rules are under review.

’nuff said