the power of curiosity

Never underestimate the power of giving students autonomy.

As regular readers (both of you :-)) will know, I have no time for practical work where students already know the expected result.

The obvious and easiest improvement is to “flip” the practical, so that the students are puzzled/intrigued/surprised by the result and have to interpret the results for themselves, or at the very least are forced to ask the question “why?” so that the theory you then teach is in response to their curiosity.

But far better still is giving students the opportunity to ask their own questions, so that they have complete control, complete autonomy.

Take my Year 9s.

We had zoomed through Enzymes and Digestion so quickly that I was suddenly faced with the prospect of starting Plant Transport in February. I don’t know if you’ve ever tried to get potometers working in February, but it’s a pretty joyless and pointless exercise.

So I thought I’d use the time to introduce some Micro-biology and let them carry out some investigations. But it’s not on the spec.! bleat the bucket filling information shovellers.

Perhaps not. But leaving aside other considerations – such as motivation, excitement, interest – it’s a great way of putting their experimental design skills into another context.

So, lesson 1, a quick intro to aseptic technique and agar plates, followed by a little mini-project – how does bacterial load on finger tips vary with stage of washing? This takes a double lesson, as they need to be clear about various points, and I want them to do it properly, all ready to look at for the following lesson. I also want them to think about Controls and Measurements. Not only are there lots of good ideas and intelligent suggestions here, but they are also already wanting to introduce their own variations (can they use hand gel? can they compare air dried with towel dried? and so on). It’s a great illustration of what can happen when you encourage curiosity and independence.

Once all the plates are in the incubator, each one carefully divided up into Unwashed (Control), Wet, Soapy, Rinsed, Dried sections, I explain that they now have the necessary skills/techniques to ask their own question. What could they use these techniques to find out?

Next lesson, they get to look at their incubated plates, and, as generally happens, they see that washing your hands appears to have very little, if any, effect on the number of bacteria they transfer to the plate! The results actually weren’t all that spectacular, with very little bacterial variation, but they’re still fascinated by what they can see, and keen to plan their own projects.

Here’s some examples of what they went for:

  • testing the 5 second rule
  • comparing the hygiene of different year groups by sampling the surfaces of locker handles for bacterial load
  • investigating bacterial biodiversity in different habitats
  • investigating the efficacy of different anti-bacterial agents
  • investigating the bacterial load of different food preparation surfaces

and a few others that I can’t immediately recall.

Actually, the questions are irrelevant – what was so wonderful was how motivated and interested and excited they were at being allowed to do whatever they liked. They will have complete ownership, from beginning to end, and their results will be their results – a real taste of the thrill of doing original research.

A very happy end to the week. I’ll let you know how they get on…

Mapping Retinas

You can’t really go wrong with eyes. Oh, unless a student starts feeling queasy with the eyeball dissection. But it’s one of those Slam Dunk Open Goal Shoo In topics that you would have to work really hard at to make dull. So the following is just throwing some random ideas out there which you might consider (if you don’t already do them).

I start by making the entire class stare at a huge red heart projected on to the board for two minutes.

red-heart-vision-trick

Then immediately switch to a white screen. They love this – it’s weird, it’s unexpected, it’s slightly unsettling, and it stimulates the obvious question – what the…?

So then we map their retinas.

mapping-the-visual-field

This is a resource I found in an age old file 15 years ago or more, so it’s not original, but I love it. Keeps them usefully occupied for 45 minutes or so and all you need is some A3 paper, sellotape, meter rules and two pen lids, one red, one green. I’ve adapted it a bit and added a homework exercise with interpretive questions to help them understand the wonderful maps that they produce…

retina-map

Once they’ve figured that out, you can go back to the red heart trick and ask them to explain it.

And if you are dissecting eyeballs, do make sure you see how high the lenses will bounce…

 

Protein Synthesis Race

And it’s back to my old favourite, Lego.

My Year 11s meet Lego as a way of understanding the link between DNA and proteins, and how the same amino acids can make different proteins depending on what instructions are being followed. See this Burble from a long time ago.

At A-level, of course, this is all covered in much more detail, but you still need some kind of fun activity to break up the theoretical background and help them visualise/conceptualise the different ideas.

I start by showing them a simple Lego model.

img_1933

What might this represent?

DNA! announces someone, engaging mouth before brain.

OK, so right idea that it’s some kind of molecule, but why can’t it be DNA?

They see that it has more than 4 types of monomer.

Try again!

This time we arrive at protein. We revise amino acids, peptide bonds and so on.

OK, so it’s a protein, and you’ve just eaten it for lunch. What happens to it?

They rummage through their brains for some Year 9 digestion memories…. oh yes, it gets broken down…by proteases… so it can be absorbed… into the bloodstream…

img_1934

We add some A-level detail – the peptide bonds are hydrolysed – but then, key question:

Where do they go?

This takes them a little longer. Go? What do you mean? But eventually they work out that the amino acids are being delivered, by the bloodstream, to cells all over the body.

Right! And what do the cells use them for?

Again, they can be pleasingly perplexed by this. It usually needs a prompt or two.

What can cells make out of amino acids?

Once they’ve worked out the answer, there’s a bit more A-level revision on the kind of proteins that might be made – channel proteins, protein pumps, ATP synthase, hair (for those lucky enough to possess hair making cells), ENZYMES!, hormones, mucus, collagen, haemoglobin – hurrah, they’re on a roll!

Right. And where does this happen? And how will all these proteins be different? So how does the ribosome know which order to put the amino acids in?

By now, they’re happy and confident and make the link to the genetic information in the nucleus. We quickly revise the basic principles of transcription and translation and why they’re necessary…

So! One half of the lab becomes the nucleus, with some chromosomes… (there’s a set for each team).

img_1936

The other half of the lab becomes the cytoplasm, with some ribosomes… (again, a set for each team).

img_1935

And a great pile of communal amino acids…

img_1930

And in teams of two, they become RNA polymerase/mRNA, in a race to find the gene (they look for a Start codon on Chromosome 7), transcribe it (on a rough piece of paper) into mRNA until they hit a Stop codon, and then sprint to the ribosome to translate their copy into a colour-coded polypeptide…

It’s great. They have to think, they have to work together and communicate, they correct each other (if one forgets to turn T into U, for example), they have to apply their understanding, and it’s competitive!

One by one they bring me their completed polypeptides. Can you see which pair were given some mutated DNA….?

img_1932

Lots of discussion points here. mRNA on a bit of scrap paper? That’s right – it’s short lived and disposable. Trade off for cell? Need to do it quickly, but need to do it accurately. Fast and you out compete other cells. But incorrect, and mutations can be disastrous…

And so on.

Half term tomorrow. Can’t wait. Have a good one!

 

 

A little bit of TLC…

I encourage my classes to bring their mobile phones to lessons. And I encourage them to make full use of the available technology – taking photos of demonstrations or practical results, looking up answers to esoteric questions, using the timer or the calculator. They know that if they start texting each other then the arrangement comes to a quick and brutal end, but I always feel that if my lessons become so dull that they’re forced to text each other for entertainment, then I kind of deserve it.

Anyway, I got my Year 13s to try something else today – using the time lapse video function to film Thin Layer Chromatography of mint photopigments. Doesn’t need to be phones – the link here was filmed with my i-pad – so if you have a class set of i-pads, you can always use them instead.

(nb WordPress won’t let me add videos without a paid subscription, hence the use of YouTube…)

As you can see, the carotene races beautifully up the strip, the phaeophytin does a great supporting act, but then the chlorophylls and xanthophyll, after a promising start, get a bit bogged down. Though look at that beautiful blue-green of the chlorophyll A!

If anyone has a better recipe for a running solvent I’d love to hear it!

And the relevant practical protocol and questions are here.

chromotography-chlorophyll-2016

I like my last question: Why is butter yellow? It seems to random, after all the carefull rf value calculation and so on, but there are so many good biological synoptic ideas tied up in this.

Have a good weekend!

Plummeting Teddies

Not a Biological Burbling this week, but a Physical one. What shall we call it? Physics is not my strong point. Physical Fumblings, perhaps? Hmmmm, maybe not.

Anyway, I’m teaching Year 8 Science. Each term has a topic and we’re half way through Forces….

Now I never got on with Forces when I was at school. I hated the apparent abstraction. Worse, I hated the fact that I didn’t understand what was going on. Sure, you can feel the force of gravity pulling a brick down, but no-one could/would explain how a stationary, inert table exerts an upward Force. Where has this Force magically appeared from? It wasn’t there when the Brick was off the table. And even quite recently, before I had to immerse myself in all of this stuff, I got quite cross and frustrated because a moving object was said to have balanced Forces – which just didn’t make sense to me.

It seems I’m not alone. From talking to the Head of Physics and others, from teaching this topic last year, it’s clearly a conceptual problem that lots of students have.

So when I sat down to re-write the KS3 SoW for Years 7&8, I had to get my head round it – after all, you can’t teach anything effectively if you don’t understand it. But also, having an insight into why students might find it difficult is vital for planning an effective teaching strategy. Indeed, if an idea or concept is so blindingly obvious to you that you can’t comprehend how someone else might not understand it, you’re unlikely to make a very good teacher. And if you’re what I now call an Ocado Teacher – someone who confuses Teaching with Delivering information – then the problem doesn’t even exist.

Last year, when I did this for the first time and was still feeling my way, I tried loads of stuff that didn’t work. Pebbles dropped into cylinders of water didn’t work as a way of investigating/understanding how Forces change on a descending object. I wanted something more interesting, more relevant, more fun. And I wanted it to work.

What I felt was needed was to take things right down to basics and provide the underlying mechanisms. Wind resistance, for example, is a familiar Force, we can feel it, name it, but if all we do is give it a name and an arrow then we’re not helping students understand what it is or how it might vary, other than with some statement like, “the wind is blowing harder”.

This was clearly a job for Cuddly Ted!

Actually, I ended up using my prized collection of fluffy birds, as we hadn’t had time to put in an order for 30 or so small teddy bears. Bear (ho ho) with me…

Context – we had covered some introductory stuff on different types of forces. They had carried out experiments with slopes and surfaces and sails, to demonstrate gravity, friction and air resistance. This was mainly about experimental design, but  we had discussed, briefly, the idea that a bigger sail has greater air resistance because it’s bashing into more particles in the air. We look at the video of a Physicist shooting himself under water. This is very cool.

Why isn’t he dead? Why does the bullet stop???

We’ve also drawn some Forces arrows. And we’ve done some Galilean “gedanken” experiments to think about moving objects in the imaginary absence of friction…

slopes-and-surfaces-3

Now I wanted to focus on what happens when you drop an object from a height – what changes and, crucially, why?

A small bear/fluffy bird, dropped from the top of the Physics fire escape staircase falls, with obvious predictability, to the ground. The class is very happy with the idea that it is being pulled down by a force called gravity (there’s a nice exercise on the Nuffield Physics Teaching site which has students lifting a brick with their eyes closed so they can feel the imaginary elastic band that is pulling everything towards the centre of the earth- they’ve done this in Year 7). They’re also happy that while the bear/bird was in my hand, the Forces were balanced, but that once I let go, and things changed, the Forces had become unbalanced.

At this point the language becomes a bit vague. Why did it fall? Because gravity was pulling down and there was nothing underneath it.

Nothing?

Well, only air.

Only air ????? Is air nothing? Did our bear/bird, now looking somewhat damp and bedraggled (it was a wet day) experience no other forces than gravity on its rapid plummet?

They remember our discussion about air resistance and atoms. The bear/bird is bashing against atoms as it zooms through the atmosphere. They blow on each others faces and experience a trillion zillion molecules bashing their skin…

So how could we save our bear/bird from a grisly plummety type of death?

Of course. A parachute.

Teams of 3. Some thread, a bin liner, some paper clips, scissors and a fluffy bird. Who can make the best parachute?

30 minutes of joyous competitiveness.The Ocado teachers hate this kind of activity – they’re not delivering anything! how can the children be learning if they’re not taking notes???!?!? Well, I could make the cheap point that the students will remember this lesson longer than any note they will ever take. but, of course, it’s all about stimulating the interest and curiosity and enjoyment that will make them want to learn the difficult bit that follows.

So, one by one, the contestants drop their parachuted birds from the staircase and I time the descent. The winner is aloft for over 3 seconds! The loser, well, their parachute didn’t open…

Back inside the lab., we tidy up, spruce up the birds, and then start work on the attached exercise.

sorting-out-forces

What I’m trying to do is provide an explanatory framework for this counter-intuitive notion that a descending object can have balanced forces. It’s structured like a story, but it’s also visual – look, there are the atoms that you bash into when you jump out of a plane. The more you bash into per second, the greater the air resistance…. why might this change…?

Have a go. Tell me what you think. Better still, if you know a Physicist (and most of us probably do) try it on them. What do they think?

For the Year 8 girls, it provoked lots of, “Oh, I see….” which is one of my favourite reactions in teaching. Come the test, will they all draw the arrows correctly….?

I’ll let you know! Back to Bioogical Burbling next week.

 

Excel and Catalase

A belated happy new year to anyone still out there in burble land.

And a brief explanation of the lack of burbling in recent months. Last term was the busiest and most stressful term I can remember in over fifteen years of teaching. For a variety of reasons, I became thoroughly disillusioned with teaching and lost all motivation to write up ideas in what little free time was available.

I cheered up a little when someone provided a link to this wonderful satirical blog on teaching https://robertpealhistory.wordpress.com/blog/ ( the  blog article: “Keep it simple, stupid”).

But then I found out that far from being satirical, it was the real deal. Worse, it’s an approach to teaching that is endorsed by that great educational reformer Michael Gove AND the Daily Mail.

Gulp.

OK, Mr Peal is working in a completely different type of school. He’s teaching a different subject. He has challenges of classroom management and pupil behaviour that I rarely, if ever, encounter.  I’m generally in agreement with his view that Powerpoint should be used to show images, not provide the backbone of a lesson (though he seems woefully ignorant of the potential for its interactive, non-linear use). And, of course, children like structure, reliability, the security of knowing that they’re learning.

But that doesn’t mean a lesson can’t also be fun, challenging, imaginative, varied, surprising…. The very last thing a teacher should be is….

Boring.

So, in the interests of balance, The Burble Is Back.

And where better to start than with Excel spreadsheets.

Ahem.

Context – Year 9 Enzymes. They’ve covered the basics of enzyme kinetics, largely discovered by themselves, and are now looking at different ways of measuring enzyme activity (rate of substrate breakdown, rate of product formation, etc).

The investigation was this splendidly challenging Yeast Catalase and Temperature activity – pretty much the same design that I use with Year 12 when they try to demonstrate a Q10 effect and have to evaluate whether and why their data does not match the predicted pattern.

yeast-catalase-and-temp-expt

I’m not expecting Year 9 to get a Q10 curve, but it’s a self-differentiating, challenging activity that is exciting, different, fun, surprising…

Now you can see from the attached homework questions that I want them to analyse and evaluate their results. But there are lots of potential problems with this. Some groups only manage to cover 2 temperatures. Others have, shall we say, technical difficulties. Others have data that shows no coherent pattern at all. Students trying to work with this kind of data inevitably end up confused – and we’re back to that horrible question that negates scientific curiosity, “what’s supposed to happen?” We need to use ALL the data in some way.

So look what happens if you get them to enter it into a class Excel spread sheet (names have been changed…) which I’ve also projected on to the white board.

9g-catalase-and-temperature-spreadsheet-december-2016-for-blog

Why does this help? Well, firstly, it adds a level of interest, and dare I say it, competitiveness to the lesson. For some reason, they just love putting stuff on the board. It also helps keep them very busy and focussed (good test of a successful lesson, I think, is when the bell goes and the students looks surprised that it’s the end of the lesson – has the time really gone that quickly?). And, vitally, they still have ownership of the data – these are THEIR numbers – they become quite attached to them in a way that just can’t happen if you pick a problem out of a textbook.

Now with our current timetable, I use the entire double lesson to carry out the practical and collect the data, so we return to the numbers in the following single. I project the completed table on to the board and immediately lots of important learning outcomes start emerging.

First, despite all the best efforts of “Shall we do the fandango?”, much of the “noise” has disappeared from the data and the means show a clear, enzyme like pattern. The value of doing LOTS of repeats is immediately apparent.

But why else might we do repeats? What else can we see? Yes, some of the numbers seem out of place. What could we do with these numbers? A bit of discussion and they see that by looking at the overall mean, and then comparing it with individual numbers in the table, we might choose to eliminate some of the data. At which point I produce this version of the table as a handout…

9g-catalase-and-temperature-analysis-exercise-january-2017

… and get them to identify anomalies. I give them about 5 minutes to do this, and then it becomes a bit like evicting contestants from the Big Brother household. Or The Weakest Link. We discuss rigorous criteria for eliminating numbers (rather than just a vague sort of “well, it doesn’t look right) and then vote on which numbers are out.

And because the numbers can be removed, live, from the projected Excel spread sheet, it automatically recalculates the mean, far more quickly and accurately than they could ever do themselves. It means they’re focussing on the actual numbers, rather than fiddling round with calculators. The rate for 70’C now drops, correctly, to zero. We can discuss why two groups found activity at this temperature and we have an evaluation point – they fess up, admitting that they probably didn’t keep it in the water bath for long enough before mixing the reagents, so there wasn’t time for the enzyme to denature.

Once this is over – and the discussion and voting is much more fun than you might imagine – they can copy the new means into the Revised Mean Mean row and they’re set to plot the graph and answer the questions.

And there goes the bell…

 

Cracking Osmosis

I can clearly remember the lesson from my own time at school. The teacher divided the blackboard (yes, I’m that old) in two with a dotted line, and we copied this, and the chalky molecules of water and sugar, and the arrows depicting the direction of water movement.

I also remember the faint feeling of bemusement. What was this all about? Mechanically copying an abstract drawing off the board enabled quality banter time with fellow class mates, but at no point did I have any concept of why this might be either interesting or important.

Since becoming a teacher myself, I’ve tried a dozen different approaches, and like to think that there has been some improvement over the years. I certainly think that this year I may even have cracked it.

So, first, why is it difficult to teach well? That’s the easy bit! It’s abstract, it’s difficult, it’s about plants, and it’s got funny words that don’t make sense. You learn a definition, maybe weigh some bits of potato, but it’s pretty dull, if we’re honest. And the osmometer? How is that relevant to anything? Yawn yuck bleurgh.

Let’s try again.

As always, I look for a narrative thread. We’ve just finished Diffusion with the homework on Mademoiselle Paramecium. meet-mr-paramecium Note the last question – it’s the bridge. We go through the other questions, and then introduce this idea that water molecules are also subject to the same rules – they, too, move.

I finished this single lesson by setting up a demo. I used to do this as a class practical, and may do again, but this year I simply gathered them round for a chat and some biological banter.

So, what’s this?

A potato!

Right. Is it living or non-living?

I love this bit. From Year 7 to Year 13, at an academically selective school, they hesitate. A potato. Is it alive? They’re really not sure! The class divides, fairly equally, into yes, no and not sure.

So what would happen if I buried it in the ground?

They twig (ho ho). Oh, right, yes, it would grow. It’s alive. Phew. They relax. I tell them about the Year 13 student I once taught who was a bit sceptical about the concept of plants as living things, but absolutely refused to countenance the possibility that they had sex.

OK, if it’s alive, what’s it made of?

They’re on firmer ground, now that the perfidy of my last question is forgotten.

Cells!

What kind of cells?

Plant cells!

Tell me about plant cells?

They duly parrot the key features.

What makes up 70% or more of the contents?

WATER!

Contained in?

The vacuole!

Lovely. Right, Persephone (or whoever), please can you cut me two chips of roughly equal size that will fit into a boiling tube.

Persephone dutifully sets about carving out a couple of chips. Much banter as she makes more or less of a mess of it. I get some of the other students to measure and record the mass and length of each chip, and then we put one into pure water and one into 1M sugar solution.

Before the next lesson, I set this out in a table and copy it ready for distribution.potato-tube-data-9g-november-2016 At the start of the lesson, we gather again around the boiling tubes and recap what we did. Then we retrieve the potato chips and measure them again. A volunteer records this new information on the board. We also pass around the chips – they are deeply amused by the contrast between the firm, swollen, rigid chip from the water and the floppy, wibbly, shrivelled chip from the sugar solution.

I get them to copy the data into their tables and write a conclusion. What MUST have happened?

Notice that I’m not interested in terminology or definitions. I’m just getting them to think about the results of an experiment and how they would interpret them. The bright ones get there quickly, the rest follow with a few prompts. The potato cells in water have gained mass. The only possible way that could have happened was if water entered the cells. The potato cells in sugar solution have lost mass. A lot of mass. The only way this could have happened was if water had moved out of the cells.

So all I want them thinking about at this stage is the idea that water moves in and out of cells.

I bring them back to the front around a sink where I have placed LOTS of newspaper. I have a balloon. I use the tap to put some water in the balloon and then hold it up. I advise proximate students to move their books and files away.

Why is a balloon a really good model of a cell?

A good discussion question this. It’s wibbly, it largely contains water, it has a membrane, and, important for KS4 students who usually think of a cell as a glorified 2D fried egg, it’s 3 dimensional.

Is this a plant cell or an animal cell?

Right. No cell wall makes it an animal cell. Like your cells.

I reattach the balloon to the tap.

Of course, I say, conversationally, water moving into a plant cell will eventually stop. Can anyone think why? Yes, exactly, the cell wall stops it.

The balloon is swelling up. Students near the sink are backing away nervously. There are lots of gasps and giggles.

But of course, you are made of animal cells. Animal cells have no structure to stop water coming in.

The balloon carries on swelling. It’s extraordinary how much water they can take on. Surely it will burst soon? Nope, it just gets bigger and bigger…. It’s great. The tension builds and builds and the challenge is to keep the merry biological banter going while the balloon inflates….

On and on it goes, until finally, with my right arm bearing several litres, and therefore several kilos of load, there is an almighty SPLOSH!!!!!! and a spectacular tsunami of water explodes EVERYWHERE, accompanied by an excited scream from the class. Brilliant. Unforgettable. Something they’ll mention at home and in their end of term evaluation and, it turns out, remember 6 years or more down the line…

Once the excitement has died down, and we’ve mopped up the water, there’s a few quick questions…

What happened to the cell? Why did it burst? Is that something you would like to happen to your cells?

This last is critical – it makes the point – water moving in and out of cells matters….

… which bring them to (continued next week…)