Teaching Waves and Sound – Ideas

An overview of waves and sound with some ideas of how you might teach them. Please add ideas to the comments or through twitter @natkin.

If we follow the philosophy of Feynman it is not about transferring knowledge without a context. If we use this approach we can go beyond simply being able to answer exam questions into the realms of learning.

I find intuition a good starting point and have written a blog post on it here

Starting with waves

Get the students to wave to you and they all can.  So they understand the concepts of waves. Have a discussion of what makes a wave, a wave.

Concept that it is a repeated oscillation about a point in language appropriate to your students

How might we describe a wave?

The students sit back to back . One can see the video of the queen waving and has to describe to the one who cannot see who has to try and match what is on the screen. I stand behind them telling them when they have got it right

If you try describing how the Queen waves in a way that everyone else can understand . Its a pain saying  “She waves her hand backwards and forwards repeatedly and quickly at the same rate without making it go very far from the central position”

Then introduce the terms

Frequency – Number of times something happens in a given time. What is the frequency of your lessons? 5 per day. Frequency of buses ? 2 per hour. Frequency of waves? Number of complete waves /cycles per second.

Amplitude – Students often confuse this with height and they need to ensure it means the maximum displacement from the rest position

Now we can say of the Queen  “She has a high frequency, but low amplitude wave”  (it seems to have changed over the years , most people remember it as slower with a higher amplitude )

Next was a demo of a slinky how might we transfer energy down the slinky? 2 ways side to side/up down or in and out

Ways of transferring energy using a slinky

Relate these to terms transverse and longitudinal waves and how there is no mass transfer of molecules, simply energy transfer. A bit of masking tape demonstrates this well.

Revise the ideas of high low frequency and amplitude with the slinky.

This may be a good time to explore the relationship between frequency and energy . This is fairly intuitive – If you walk into the sea and waves hit you more frequently then you will clearly notice that higher frequencies transfer more energy. Relating this to the electromagnetic spectrum waves of frequency greater than that of visible light – Ultra violet and higher can be dangerous.

We can also see wavelength clearly demonstrated on a slinky

You can see nice standing waves using an electric toothbrush and elastic outlined here

You can also demonstrate  wavelength and it’s relationship to velocity using a hand wave. Give them a pen to hold over a sheet of paper. Pull the paper with an increasing speed and you will see an increasing wavelength being drawn on the paper (see below) You can also relate this to the wave equation

Velocity (m/s) = Frequency (Hertz) x Wavelength (m)

The frequency is constant and the wavelength increases as the velocity increases

Excerpt from a lesson

Having had the terms described using Pose/Pause /Pounce / Bounce to gather their ideas they were then given 2 minutes to perform waves of high/low frequency, large/small amplitude and long/short wavelengths. Some interesting ideas were demonstrated with students also whistling high and low frequencies. I know I am teaching well when my students surprise me.

Jelly Baby Wave machine

Then they were given a length of duct tape, barbeque skewers and jelly babies to make the jelly baby wave machine. seen here

This is an ideal experiment to get the students to build the problem. What might happen if …?

Ideas:

The distance between the sticks was changed

The tension was changed

The jelly babies were moved closer to the centre

Half of each jelly baby was eaten

Sound

Following the concept of waves leads us into sound a longitudinal wave. Show with a slinky

Other possible demos

Frequency and Sound

Hum the National Anthem with your hand on your throat. Hum in louder (higher amplitude) , higher frequency etc. What do you notice?

Vibrations of your vocal cords. What would happen if you have no vocal cords after say a larnygectomy

How can you make a metal rod sing?

Hearing Tests

If there is only one thing to tell students it is that every loud sound damages your hearing. In quiet societies old peoples hearing is far better than it is in noisy societies .

An online hearing test is here

http://www.actiononhearingloss.org.uk/your-hearing/look-after-your-hearing/check-your-hearing/take-the-check.aspx

The worlds quietist room where you can hear your organs !

Following this you can go into the realms of making music and the straw oboes

http://www.physics.org/interact/physics-to-go/straw-oboes/

Ask the question what would happen if…?

The straw became very short? – Would go into ultrasound

The straw became very long? – Would go into infrasound – which may attract elephants

Can you shatter a glass with just your voice?

This can lead you into resonance and the must use footage of the Tacoma Narrows Bridge

and this truly spectacular demonstration

Taken from here

Or make a very annoying sound from a piece of paper that will make the other teachers hate you

Speed of Sound 

You can use Audacity – free and brilliant software to measure the speed of sound

National STEM Centre resource here or

Or by echoes

Speed of sound with echoes

Apps for Sound

String for iPad – Simple app that lets you play with waves on a string here

Higher level em spectrum stuff  from Loughborough here

Fourier Touch – Great for showing beat frequencies and playing with sound waves here

Review of these 3 here

There are a few oscilloscope apps around. I use oscope here

Lots of sound level apps that are great to leave on to keep class noise levels at a reasonable level.  Decibel 10 gives you peak values etc here

Not sound as such but the seismometer app is useful here

Uses of Sound

10 wonderful uses here

Really interesting list here might need some verification

Making instant coffee in mid air – Acoustic Levitation here

As a weapon – Anti piracy or demonstration devices LRAD (Long range acoustic devices) – report here

Feel free to add ideas to this through comments etc – I’m constantly updating it

Getting your students to really think independently

What are the answers to these three questions?  Try to solve them before reading further

1. (1)  A bat and a ball cost $1.10 in total. The bat costs $1.00 more than the ball. How much does the ball cost? _____ cents
2. (2)  If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets? _____ minutes
3. (3)  In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of the lake? _____ days

These are taken from S Frederick  Cognitive Reflection and Decision Making (2005) . Each question has a compelling answer that is wrong. Intuitively we assume the ball costs 10 cents, 100 machines would take 100 minutes and half the lake would be covered in 24 days.  Correct answers at the bottom of the post. In tests 65% of students made at least one mistake. When the questions were then made hard to read by greying out the writing, performance improved dramatically with now only 35% making mistakes. The full research paper is here

This seems counter intuitive, performance was improved by adding a difficulty?

Another piece of research that seems to support this was the following

Line 1 is easier to read, but that lines 2, 3, and 4 are easier to remember and may help learning new material.

Researchers at Princeton University and Indiana University conducted two experiments to determine if changing the font of material would improve memory and learning. In the first study, people (18 to 40 years old) were given 90 seconds to memorize information written in different fonts. They were given a memory test 15 minutes after they memorized the information. The subjects scored 72.8% correct when they memorized information in the easy- to-read text (Arial font, line 1 above), but the scored significantly better (86.5% correct) when they memorized information written in the difficult-to-read font (Comic Sans MS font, line 2 above).

This also seems to fly in the face of the fundamentals of teaching. Surely the simpler we can explain things and the easier students  can access information, the better their learning will be?  Evidence seems to suggest this is not the case

Dr Derek Muller, who has a brilliant physics videofeed under the name of Veritasium, looked at using multimedia to support learning. His full PhD thesis is available here but a useful summary is

It would appear that simply giving the information to students, even if it is to us clearly at odds to their prior beliefs, can often just lead to them misinterpreting it and instead using it to confirm their own bias. We have many biases, an overview is here , one of the most powerful is probably Bias Blind Spot – the tendency to ignore our biases!

Teaching would be a very simple process if humans were rational and eager to learn from us. In his superb book Predictably Irrational – Dan Ariely outlines some of our bizarre behaviour patterns. The chapter on how arousal affects our decision making processes is particularly frightening, for example 5% of the respondents  said they would consider using a date rape drug in a non aroused state – this rose to 26% in an aroused state.

The advent of online courses such as MOOCs and Flipped Lessons might to some start signaling the end of teachers. Those who believe this are missing the point. Teaching is a two way process and cannot be reduced to it’s tools. This has been nicely outlined in Aaron Barlow’s blog here. A skilled teacher can never be replaced by technology as they understand that giving information is only the starting point and that whatever your teaching style you adapt to the needs and responses of your students. More importantly we have to challenge our students assumptions and force them to make a mental effort and to move away from spoon feeding.  This involves forcing them to go beyond the shallow and immediate response into deeper thought. This is not something most will welcome. Safety is a more powerful driver than exploration to many. A nice maths blog by John Smith  – Penny Drop Teaching here  makes a great point – Are we simply rewarding those who make the least mistakes or developing the best mathematicians? this applies to every subject.

I am a huge fan of the 3 Act Maths approach by Dan Meyer  which I have blogged about before here and supporting it with technology and ave started developed the science of here

The idea is that students are shown a video/demo of something and asked for what questions it makes them think of then an intuitive response,  the students build their own problems then delve deeper into it. It makes them question their automatic response before leading them to the ‘reveal’ ie what the answer might be.

Is there any theory which supports 3 acts? To me this takes students into the realms of dual process theory  and the work of Daniel Kahneman starting with system 1 and then forcing system 2 into action but using the students own motivation to do so.

In his book ‘Thinking Fast and Slow’ Nobel Prizewinner Daniel Kahneman splits the brain into 2 systems.

“System 1 operates automatically and quickly, with little or no effort and no sense of voluntary control”

“System 2 allocates attention to the effortful mental activities that demand it, including complex computations”

So system 1 is fast, intuitive and emotional, while System 2 is slower, more deliberative and logical. System 1 thinking is for example recognising a teacher or answering the question what does  2+2 equal, while an example of System 2 thinking is finding your way to a new classroom or what is 27 multiplied by 43.

When system 2 is in action, for example in  trying to solve the 27 multiplied by 43 problem you may have to stop other things that we are doing (it wouldn’t be sensible to try and solve this when overtaking in a car for example) The harder you find maths , the bigger the load on your brain and you may enter the realms of cognitive overload if other things are competing for your attention. This is clear to any parent who tries to have an in depth conversation when looking after a toddler, it is next to impossible.

Whilst engaged in system 2 thinking our pupils will dilate (could this be a use for google glasses – to analyse the level of our student’s thinking?) and our blood pressure and heart rate rise. It is a conscious action, heavy on resources; glucose consumption rises rapidly and we soon feel tired. Many people have a reluctance to use system 2 so System 1 is the one that usually deals with things.

Our sense of who we are is based on System 2, “the conscious, reasoning self that has beliefs, makes choices and decides what to think about and what to do”. But our self  that is most apparent to others is System1 as it “effortlessly originates impressions and feelings that are the main sources of the explicit beliefs and deliberate choices of System 2”.  System 2 is portrayed by Kahneman as the supporting actor who considers themselves to be the lead which is usually taken by System 1. If we used the slow System 2 all the time we would scarcely get things done. Consider the mental effort the first time you ever drove a car to being an experienced driver. But in order to learn something new we have to have System 2 working and this is where a skillful teacher comes in. We have to find a way of getting past the guards that are System 1 and a powerpoint or video designed to transmit information is unlikely to help you .

The average pause time for a teacher between asking a question and getting a response is too short to invoke System 2 so we tend to get an automatic System 1 response from those who already know the answer. This has very little purpose as it is unlikely to influence those who don’t know the answer and is simply a way of those who already know showing knowledge. An interesting alternative to this question- response , new question – response that Dylan Wiliam likens to playing table tennis with one student, reducing the rest to passive observers, is to involve all by employing a more basketball like Pose, Pause, Pounce, Bounce as outlined by @teachertoolkit here .

Technology now has the potential to give teachers unparalleled insight into our student’s prior knowledge with the likes of Socrative and the promising looking Answerpad if used as part of an effective Assessment for Learning strategy so we can see their starting point. We can track student thinking with the likes of educreations , Explain Everything or iMovie. This means we are no longer simply presented with just an answer we can also track the students learning journey and give feedback along the way Showbie is particularly good for this. I’ve outlined a lesson using these here

By teaching students to pass tests, we can equip them with simple, or even quite sophisticated pavlovian System 1 responses that will get them a good grade. They can answer the questions because they have practiced many similar questions so know how to decode the exam paper. This strategy leaves them vulnerable to any slight change in the style of the exam question. We can be guilty of giving them fish, rather than teaching them how to fish due to the pressures of the current system that encourages risk aversion. Are we preparing our young people perfectly for a world that no longer exists, highly qualified, but poorly educated ?

To me the 3 part Maths or Science clearly uses System 1 and System 2 very effectively. Possibly most importantly it also gets our students to question whether their intuition gives them the best answer and encourages deeper thinking that will equip them with the challenges for life.

Of course the 3 acts are a supplement to other teaching methods and tools and they lead to improvement in performance as well as learning

At this point it may be useful to consider performance separate to learning

It is possible to have improved performance without deep learning

If you’re after rapid improvement (performance) then you make your teaching predictable, give students clear cues about the answers you’re looking for, and do a whole load of massed practice. If you watch that lesson it looks great! The teacher is happy, the students are happy and the observer can tick delightedly away at their clipboard. Come back and text them next week, next month, next year and the situation is a little more bleak.

David Didau

Finally we can look at the culture of our classroom to promote thinking . There is evidence that focussing purely on performance and particularly comparing the performance of classmates leads to a reduction on thinking about the task and an increase in thinking about the outcome. In this great video Alfie Kohn argues in the video below passionately and (to my bias) compellingly for change. He says that in performance orientated cultures students choose the easy route not because they are lazy, but because they are rational. I will give you what you want with the least effort possible. Looking at the work of Carol Dweck we want our students to see their success or failure as something they have control over not – I succeeded because I am clever/was lucky/it was easy turns into at some point I failed because I am not clever/was unlucky/it was hard – something that makes them powerless to do anything about. A fuller and more eloquent review by Alex Quigley @huntingenglish is here

So before you teach next please consider how you are going to challenge your students to really think and to engage System 2

Answers to questions:  5 cents, 5 minutes and 47 days

Comments and suggestions welcome

If you are not perfect, you are not yet finished

There seems to be a battle raging on twitter with a divide between didactic and interactive teaching partly stoked by Daisy Christodoulou’s book Seven Myths About Education. I don’t really get it. Delivering purely one or the other doesn’t make sense to me. It’s a bit like arguing over whether a saw or a drill is the best tool. Simply be the best that you can be at both, make the most of what you are good at and get better at the rest. To borrow and corrupt a term quoted by David Didau (If it is not perfect, it is not finished) if you are not perfect, then you are not finished. In any lesson I need to impart some knowledge and also need students to explore their understanding, to do something with that knowledge. If I don’t do this it is like teaching them how to swim but without water. They can answer exam questions on the technique of swimming, but they cant actually swim, nor know the joy of applying it to be able to snorkel, scuba dive, surf …

This post is based purely on my own beliefs and experiences, because it is the only thing I feel qualified to write about.  I am still not a finished product, nor will I ever be, irrespective of books read and experiences encountered. That is to me the endless fascination of teaching. I am still a long way off perfection, but twitter and blogs are helping me go in the right direction

I am not a huge fan of educational research as I cant see how we can evaluate the effectiveness of strategies that can work brilliantly with one class and bomb with the next. The variables that can affect the outcome can be the weather, the temperature, the wind (?) , a fight in the morning, the teacher in the lesson before you, a boring assembly…. this is before you even start to consider the moody bunch of young people in front of you. How on earth can we ever get valid results with this many variables?

I can see that google can replace the learning of facts if that fact does not interconnect with anything else , but I cant think of a single example in science where this is the case. I will never be able to see how things fit together if I rely on google. It would be like trying to construct a jigsaw puzzle but some of the pieces are in different boxes and I have to find them myself by searching. This is compounded by not even knowing what the piece looks like. I would argue that it is more important to consider when the knowledge is taught and to me this is when the students realise they need it. When they realise there is a piece missing as I wrote here , however this may just be me confirming my bias as this is the way I learn best.

I have seen too many lessons where students carry out experiments for no real purpose, but also ones with students totally switched off as a teacher drones on. From a personal point of view I would rather have exploration, as in this case I am not restricted by the teacher and may will learn something. In some elite schools I have seen brilliant teaching, in others the students have learned despite their teachers, doing well in exams but not considering carrying on in science at a higher level.

There is a lot of fantastic debate intellectualising teaching and I have learned hugely from this, but some seem to  ignore the complexities and motivations of those young people in front of us.

I teach young people science, not science to young people. There is a fundamental difference; it is a two way interaction between human beings. I see in front of me, fragile, beautiful, complex, frustrating human beings hormonally programmed to fight me. I treat all of them as I would want my own children treated. I don’t always like them, but I have a duty to them. They have one shot at education and I can inspire or destroy. It may sound corny , but I like Khalil Gibram’s ideas – I am the bow and they are the arrows. I send them forth into the world, hopefully equipped to deal with the trials and tribulations of life, but not dependent on me. Their success goes beyond exam results, if they give up and don’t see the relevance of my lessons I have failed them.

It may or may not be more efficient in terms of their scientific knowledge to treat students as vessels to be filled and indeed it may improve their performance, but I am interested in learning above performance. I want my students to do more than pass exams, to be able to apply scientific reasoning to all situations. They shouldn’t be vulnerable to exam questions worded differently. This is science for life, not as an abstract concept. I also firmly believe they need knowledge, lots of it otherwise they will never see the interconnections between concepts. However the giving of knowledge without a clear purpose approach seems strange to me. Like teaching them how to use all the tools needed to build a boat, the drill and the saw, but they never get to see it, let alone build it.

I dont seek to make them like me or to compress them.  If they surprise me I know I am teaching well as I haven’t limited them. I don’t want or make them do things simply to show that I can, to force compliance. I am in charge , I am the leader with non negotiable rules and this is about learning. I cannot make them learn, but I can stop them interfering with the learning of others. I have taught many students who are more intelligent than me, but few I consider wiser, wisdom comes from experience and failure. I want my students to be resilient and not see failure as the end, simply as a learning experience.  I am a product of failure, because I have taken risks, have gone too far, learned from it and have then gone too far again.

@oldandrewuk one of Mr Gove’s favourite blogger talks a lot of sense but I have to take issue with some things in this post

Lies, Damned Lies and Things You are Told During Teacher Training

He says not to assume these are true, I feel we should assume them to be true unless there is evidence they are not.

1. Children learn better when they are happy. – I’d rather my kids were happy as there is no evidence that happiness is a barrier to learning.
2. A good lesson is entertaining – No, but it has to be engaging.
3. Good lessons result in good behaviour – Not always true, but bad lessons usually result in bad behaviour
4. Behaviour is determined by the relationship between student and teacher. – Depends if you are looking simply for compliance or engagement. A shared journey based on mutual respect vs a whip.
5. Lessons need a variety of activities. There is evidence for multi – modal learning being more effective and a fundamental of human fulfillment
6. Learning will result from discussion between students. – See the work of Prof Mazur
7. Children are more interested in topics relevant to their lives.  I feel they are better at applying concepts to things they can relate to.
8. Knowledge and understanding can be distinguished and taught separately. Interlinked
9. Children like using technology. – Their future will be digital and interconnected if we dont teach them to use the tools we are failing them.
10. If you teach well, your students will like you – It’s not a popularity contest it’s about equipping them for their future, but if you teach badly they wont like you for good reason!

Advice given to me by my father (a teacher ) :  Be yourself, be the best that you can be and never stop learning

5 blogs, chosen  out of the many I have found useful that you may want to read

Tom Sherrington www.headguruteacher.com

John Tomsett http://johntomsett.wordpress.com

David Didau www.learningspy.co.uk

Kev Bartle www.dailygenius.wordpress.com

Mark Anderson  http://ictevangelist.com

iPads in Science – Transforming learning?

A brief overview of how I have been using iPads to transform science lessons . Using the SAMR model I am really only interested in redefinition. Using the iPad to do things I cannot do without them.

Wordfoto – here  a great app for literacy – create the image from the key words

 

Slopro  – here 

An app that turns your device into a high speed 1000fps video camera. This allows us to see things happening that we cannot see without them.

A perfect example of this is a lesson at Leicester City College I did with the talented Tom Harbour (who came through Teach First and is a glowing testament to the programme)

The principles follow Dan Meyer’s 3 Act science which I have blogged about here and the science element here.

Students were shown the cup and the key experiment. A key and a cup are tied to opposite ends of a string about 1 metre long. The string is then hung over a pencil and the key held horizontally – See the video below.

The students were asked what questions it made them think of? and from Tom “What would happen if ….?”

Note: the fabulous app Socrative  here would be perfect for collecting student’s questions and thoughts

Unfortunately having filmed in slopro we didnt have enough time for the analysis so I have done it using

Coach’s Eye here Primarily designed as a sports analysis app, it is also ideal for analysis of forces.

This allows you to annotate the video and provide a commentary as you do so

(It has to be said that the position of the arrows on the video are slightly unfortunate ! )

iMovie then allows videos to be combined and becomes the app that brings everything together

Showbie  here is a fabulous app that allows work to be set , seen and marked online and instantly with a range of different ways of communicating via voice, photo, video and pdf documents

View the class (and see what work they have done )

They can contribute or you can mark in 6 ways

A photo of their electric motor (Hmmm!)

An annotated video of their work

Please feel free to add or comment on these ideas

Matchbox Coin Challenge

Push a coin into a matchbox on the base side of the inner box as shown

The challenge is to get the coin to go upwards through the box to come out of the top, but you can’t touch the coin. I was shown this by the wonderful Syailendra Harahap

What are you going to do?

Dont watch the video below until you have tried to solve the problem (really don’t watch it yet!)

When you do watch it pause the video between Act 1 and Act 3 whilst you think.

Act 1: You are going to tap the top of the box. What questions does this make you think of?

Act 2: What might happen if…. ?

• You tapped the box harder?
• You used a lighter/heavier/bigger coin?
• you used a full matchbox/heavier one?
• you used a bigger matchbox

Act 3: The reveal

So what is happening?

The coin cannot be moving upwards as the only force that is exerted is downwards.

The coin starts in a state of grip with friction holding it in place in the box.

As the box is tapped it moves downwards, however the coin has inertia and so does not move with the box, it stays fairly still whilst the box moves past it. The frictional force is in a state of slip at this point and the box moves relative to the coin. As the box slows down friction returns to a state of grip. The coin appears to be moving upwards inside the box and will continue to do so until it reaches the top.