Category Archives: KS3

Gel electrophoresis

Not much to say this week, just some pretty pictures. It’s a kit supplied by Carolina Biological and our wonderful technician of the year suggested that it would be a suitable activity to include in the new Year 7 Separation topic. It’s an introduction to the concepts of Gel Electrophoresis and it works….

…. well, see what you think! Here’s the set up, with a bit of white card below the tank to help see what’s going on…


The gel runs in about 15 minutes with a decently powered pack so it fits into a double lesson…


The protocol separates various dyes and includes 3 unknowns for the students to analyse.


They absolutely loved it.

Who’s your daddy?

I’m making this the last Burble of this Academic Year. It’s partly a feeling that inspiration is close to running on empty and partly sheer exhaustion. I need a break – as I’m sure you all do too.

I was going to just post some of my favourite pictures of recent work….

…like this spectacular mitosis slide found by a Year 12 student preparing a garlic root tip squash with Orcein stain… (and captured with the Celestron digital microscope imager)


… or this fabulous gel, just one from our best ever results with protein electrophoresis. I’m adding to our formidable supply of gel tanks, acquiring enough vertical versions so that we can run more appropriate protein gels with polyacrylamide, but the one on view here is a bog-standard horizontal agarose.


OK, I wasn’t too impressed with the forensic inquiry of the students – 4 lanes of chicken breast vs 4 lanes of chicken nugget – couldn’t they have included some other parts of the chicken for comparison?!?! – but look at the bands! Photographing with an i-phone or an i-pad also allows for instant fiddling with the picture,  making it black and white and adjusting the contrast to make the bands clearer.

But today was Year 7 Baboon Day, my favourite day of the year.

The full details of this lesson with all the relevant resources can be found here:

Who’s Your Daddy?

So having already role played cuckoos and host birds and rats in Skinner boxes, they now get to role play baboons, whilst half a dozen students try to figure out what’s going on, collect molecular data by “darting” the baboons to get “blood samples” and so on.

All good fun and, as usual, they made splendidly realistic baboons. But the best features of a lesson can sometimes be the unexpected ones. The students cast as scientists had done a great job as field biologists, but were having particular difficulty determining the paternity of the baby baboons. The mothers and babies were fine – the DNA profiles were consistent with their field observations. But who had fathered the offspring?

I couldn’t understand the difficulty. Once you realise that all the bands from a baby must either match bands in the mother or father, so you have to account for all bands present, it’s just a simple logic problem. Isn’t it? But, no, they were baffled. What was the problem? Where was the mental block?

And then one of them had a flash of insight.  Hang on, she said, are baboons different to humans? Can one father have several “wives”?

It was a brilliant moment, a lightbulb moment, one you want to capture and bottle and share with the world. They had been trying to match up mothers and fathers and offspring as discreet, family units. This hadn’t worked and they were getting frustrated and confused. Suddenly, with this new way of looking at the world,  they could make sense of it all. They rapidly worked out that the alpha male was not only the father of 4 of the 6 offspring, but had (shock horror!) sired them with 4 different females.

This is quite sweet – such innocence! such well brought-up students! – but I love anything that startles students out of pre-conceived views of the universe. They had framed baboon society as being essentially the same as conventional, middle class, western human society, and subconsciously made certain assumptions. Which didn’t match the evidence. So something had to give.

Before they left for home, I asked them what they had learned in the lesson. The list was long – dominance hierarchies, stress hormones, grooming behaviour, DNA profiles and how to interpret them, baboon society, field biology, how to communicate without speaking….

And they hadn’t written a single thing down.

Have a great summer. I hope to be back in the autumn with more ideas to share.




Sheep Dash and Water update

Last week I wrote about a last minute lesson plan emerging from a fog of exhaustion and panic (a Groundhog moment from the first year of teaching where every single lesson is like that!). I’m pleased to report that the lesson in question was a great success, the Year 8s enjoyed the activity and could almost immediately understand and explain the difference between their two sets of results ( see attached exercise here Sheep Dash experiment). I also made use of the class skeleton and a spare Chromebook to talk them through the sequence of events that take place from the moment that the sheep makesits dash, to their successfully(or not!) clicking the dart gun.

IMG_0830 IMG_0827

I’m following that up with a simplified version of Bill’s marvellous Brain Injury exercise (also see last year) which is an excellent example of how you can turn what could be a dull lesson in information delivery into a lesson of learning and discovery. It’s based on the fact that most of what we know about brain function was originally deduced from linking an injury to a specific region of the brain (stroke being the classic example), to the symptoms that follow. Students “damage” localised areas of the brain and are told the resulting symptom(s) – they then try to infer what that part of the brain does. (brain injuries) It’s also a great illustration of the potential of Powerpoint, where the direction of the lesson is determined by the students’ choices, not by the linear construction of the slideshow. Have a go! It’s strangely addictive, even when you know the answers….

The new Year 12s are adjusting to life at A-level. I talked last Year (22nd October) on my introduction to Water (which is also my introduction to the A-level course). One girl this year got the HIJKLMNO(5) clue in less than a second (literally!) which given that I normally expect this to take 5-10 minutes, rather threw my lesson plan. But once the water circus and the water properties homework is out of the way, I then go back to the importance of the solvent properties, particularly the idea that metabolic reactions take place in solution. I talk about the origins of life. I talk about Miller and Urey and show them this (amino acids intro it’s another one of Bill’s splendid animated Powerpoints), stressing the idea that in certain conditions, complex organic molecules can arise spontaneously out of simple ones. But there’s a problem….

I herd them all into a corner of the lab. You’re all complex organic molecules, I say, amino acids and nucleotides and stuff, all in solution, pouring out of that cold vent in the ocean floor. The rest of the lab is the big wide ancient ocean, 3.5 billion years ago. If you could only bump into each other, we could get life kick started! But what happens….?

It’s lovely. They all drift apart, sub-consciously (perhaps) recalling Year 9 lessons on Diffusion, until they’re evenly spread throughout the “ocean”. I stop them. What’s happened???? Why can’t you bump into each other???? Oh no! Life is never going to happen… unless…. What else must we have? They instantly see the need for some kind of enclosing structure to stop them diffusing irrevocably apart. What do we call that enclosing structure? A cell membrane! Aha! And what property, I say, must a cell membrane emphatically NOT have????

This last question usually requires a few seconds thought…. Someone might suggest “permeability”, which is fine – I praise the answer and then park it for a future lesson – but what else? Given what they’ve just done, what property must the membrane NOT have? Yep, that’s right, it must not be soluble in water. Which means it must be made out of something…? Hydrophobic. Can they think of any common hydrophobic organic molecules….?

This launches us into Lipid chemistry and the background to cell membranes, one of my favourite topics on this or any other specification.

I structure it this way because I like the story, the logical sequence (rather than sticking water into a random lesson half way through the course), and the evolutionary context. I like the way it stresses the primary role of a membrane – which helps when we come on to compartmentalisation – and I always like getting them up out of their chairs and doing something, even if it’s just role-playing an amino acid in an ancient ocean….

Lesson Planner’s Block

Welcome back to Biological Burblings, and welcome to a new academic year. I hope you all had wonderful summers.

It’s been the usual hectic start to the autumn term. Not one, but TWO (joy) days of INSET, or professional development, or whatever you want to call it (I could think of a few choice words….). Then a day of students in school but no teaching. And then, on the Friday, I took 27 Year 13 students to darkest Somerset for the Biology Field Trip and a full set of ecological Practical Skills Assessments. More joy.

Actually, the field trip is a genuine joy. Nettlecombe Court ( is a glorious setting, an old red sandstone stately home surrounded by deep valleys and ancient woodland and some of the biggest trees I’ve ever seen anywhere. The students are invariably brilliant, we always seem to catch the best of the early September sunshine, there are endless cups of tea and cake, and it’s a gentle way of easing back into the term after the summer holiday. With the abolition of PSAs (I have a bottle of champagne set aside for when I mark the very last one of these wretched distortions of scientific inquiry), there is no longer a compelling reason to organise a field trip, but I’m pretty confident we’ll retain it. It’s popular, successful and enjoyable and – with the OCR Biology A course – there needs to be some ecological investigation in the practical portfolio. I rather like the idea of letting students ask their own questions and design their own investigations. What are other people thinking?

We returned late on Monday, so actual teaching didn’t start for me until Tuesday. Four days of lessons later and I already feel exhausted….

….but we’re up and running. This year I have three Year 13 classes, two Year 12 classes, a Year 7 and a Year 8, as I continue my self-appointed task to re-write the KS3 Scheme of Work. So I’ve got no iGCSE teaching at all. The Year 12s are underway with the new A-level, but still starting with Water – see my blog from 22nd October last year for ideas on this. A colleague of mine also had the wonderful idea of freezing equal volumes of water and olive oil in separate plastic cups. The comparison of volume after freezing is dramatic and, better still, the frozen olive oil cube sinks like a stone in liquid olive oil.

I teach both sides of the Year 13 course, so two groups have tackled Squiggle Chemistry, where they figure out Chemiosmosis for themselves using the same evidence that Peter Mitchell used (Squiggle Chemistry) whilst the other one has launched into maggot innate behaviour experiments and the chance to try out their new found statistical knowledge. For any of you who don’t like teaching statistics, try introducing the Chi2 test with the opening from Rosencrantz and Guildenstern Are Dead, by Tom Stoppard. If you don’t know the play, here’s one version of the first scene ( And here’s the script
The play starts with the two characters gambling by flipping a coin – which has come down Heads 85 times in a row. The winning character, Rosencrantz, who gets a gold coin every time it comes down Heads, is a bit embarrassed but clearly not too bothered. Guildenstern, however, is deeply disturbed, not because he’s lost a shed-load of money, but because there’s something funny with the fabric of the universe. A coin cannot come down Heads 85 times in a row….I ask the students at what point they would stop playing. And introduce the idea that statistics is basically just a way of finding out if you’re being cheated – or if something funny is going on. It’s also a nice way of thinking about alternative explanations – if something doesn’t match your Expected, how could you explain it? Loaded coin? Double headed coin? He’s lying?

As for the KS3 classes, I’m reviewing and revising the Year 7 lessons that I wrote last year, whilst writing an entirely new SoW for the Year 8s. I love the excitement and creativity of generating new lesson plans, but because the Science lessons are standardised across the two year groups, it also means I’m planning new lessons for 3 other teachers who, understandably, want to know they’re getting something good and reliable. That’s quite stressful. I can go into my own lesson completely unprepared and improvise, busk, entertain, distract. But I can’t expect other people to do the same.

And on Thursday night it almost came unstuck. I was shattered, absolutely cream crackered, barely able to keep my eyes open, only just awake. And I had to have a new lesson ready for the next day. I knew what I wanted to do – something on the Nervous System to link to the work they had already done on muscles and bones. But my mind was blank. I scribbled down some random thoughts on how to introduce the topic. But what then? I wanted some kind of experimental investigation that would be fun and different and memorable. The old course was extraordinarily content heavy – masses and masses of facts to be delivered and regurgitated on demand. I want to pull it to the other end of the spectrum – no notes, not much talk, lots of Learning By Doing. But it wasn’t happening for me. My mind was completely blank. Sure, there’s lots of stuff out there, but I was reluctant to steal stuff from the iGCSE course, even if part of me was saying, “oh, just do the ruler reaction time practical, or the skin sensitivity practical.”

But I had no inspiration. So I got up and walked around and did the washing up and turned the children’s lights out and got my stuff ready for the next day….

And then went back to my desk and wrote a lesson plan based around the Sheep Dash game Which would be quicker, to dart the sheep by watching them? Or darting the sheep when they hear a friend say “baaa” when they see a sheep run across. There’s data to collect, means to calculate, graphs to draw, comparisons to make and explanations to explain. It’s not the greatest lesson in the world, but they’ll talk about it when they go home and I’ve bought an extra week to think of the next two lessons….

Pressing none of the right buttons

So, last week I made reference to a Year 7 lesson on Animal Behaviour  that I thought people might like to try. Scanning back through previous posts, a kind of retro-burble, I notice that I had already mentioned this in passing as part of a Year 13 lesson. Given that the new A-level specification has completely removed any mention of Animal Behaviour as a Biological topic (why? what were they thinking?!!? absolute madness!!!!) I have simply moved all the wonderful practical activities down to KS3 so that our students get at least some exposure to this fascinating area of Biology.

Which brings us to Skinner Boxes. This follows rather neatly from the work they did with Hettie and Herbie (our hamsters) in their splendid cardboard mazes. After a brief review of the pros and cons of studying behaviour in a laboratory setting, I explain that today they will be working with a brand new animal. Can they guess what it is?

I leave most of the girls in the lab, under the supervisory gaze of our technician, and take two of them (pre-selected) into a neighbouring lab. Here I show them the “Skinner Box”, simply some tables rearranged to enclose a small, square area, with a button-operated bulb on each side (your Physics technician can run up a pair of these in 5 minutes or less). I explain to the two girls that they will be operating the Skinner box. This involves following the instructions on a series of experiments (Skinner box operator instructions 2 Skinner box operator instructions 1 where “rats” (i.e. Year 7 girls) are put, one at a time, into the box and allowed to explore their surroundings. The operators sit outside the box, opposite each other, with a box of Maltesers (to provide suitable rewards), and a long ruler (to provide “punishment”) each.

They quickly grasp what they’re meant to do. I tell them to keep the Maltesers out of sight, under the desk, and to not let anyone else read the instructions. For the first series of experiments, every “rat” will be a sample in Experiment 1 – the “rats” simply have to do is press the button and light up the bulb – if they manage this, they get a Malteser….

I go back next door. Have they guessed the animal yet? Mice! Woodlice! Guinea pigs! Rabbits! No, it’s a much simpler animal. Very basic instincts. Very readily available in a school setting. At this precise moment you are never more than, oooh, 50cm from one…. Oh, is it us? Bingo!

I tell them that they will play the part of experimental rats. That I’m going to take them one by one into my other laboratory and observe their behaviour for 15 seconds. That’s all. They’ve seen how hamsters behave in a strange setting – just pretend you’re a hamster. And I will be filming it all on the department i-pad.

And we’re off. Olivia, the first “rat” in, provides a textbook example.  She snuffles around inquisitively and, with seeming inevitability, presses a button. Flora (one of the Skinner Box operatives) dutifully delivers a Malteser. Olivia giggles with surprise and delight and immediately presses the button again. Voila! Another Malteser is provided. I quickly stop her because I don’t want the Maltesers to run out – she’s got the idea, she’s learned the association.

Experimental rats get to watch the other rats being tested – it’s partly the logistical difficulties of having yet another holding area, but mainly because I want them to see and enjoy what’s going on.

At this point, something rather surprising happens. The next 5 girls do nothing – literally, nothing. They stand there, all self-conscious and slightly giggly, some not even looking around, but absolutely refusing to risk doing anything in case it’s wrong. “What am I supposed to do?” some of them mouth at the other girls, but they are under strict instructions not to give any clues, and after 15 seconds I put them out of their misery (i.e. I stop the experiment – I don’t put them down humanely!).

Sofia, rat number 7, behaves just like Olivia (hurrah!) and then, joy of joy, in steps Maria who just decides that she will spend her 15 seconds spinning like a whirling dervish, her long blonde pony tail whirling behind her. “I’m dizzy….” she gurgles delightedly as she staggers out of the test area. By now, of course, every girl in the room now realises that they should have done and while feeling rather foolish and frustrated, they’re also enjoying seeing others miss the point.

By the end, only 5 out of 20 girls were sufficiently curious and lacking in anxiety to win some Maltesers. The rest just didn’t want to risk doing anything in case it turned out to be wrong, whatever that might mean. Where does this fear come from? Our education system? Our nationality? Can we blame Michael Gove? Whatever the reason, it makes for a good life lesson. Take a chance! Just do it! What’s the worst thing that can happen? You might win a Malteser!

Of course, having now all seen the kind of thing that’s going on, they’re all suitably prepped for the second round of experiments. This time I let everyone watch, because all the experiments are different. And now they are wonderfully imaginative and creative in their quest to get the right behaviour pattern. I particularly like the girl who just stands in the middle of the box and says, very quietly and politely, “Please can I have a Malteser?” Some girls find they are being prodded by a ruler – which continues until they press the button. And so on.

It makes for terrific discussion. How is this different to the maggot behaviour? Which is better for learning, reward or punishment? Should you revise with chocolate or electric shocks? And where are the real life examples of this kind of learning? This last takes them a while, but they eventually come up with learning what stinging nettles look like (could be a good comparison to start the exercise – demo lots of different leaves – which ones do they know), and the warning colours of bees and wasps.

Learning about Learning by doing – the only type there is.

And that’s nearly yer lot for this year. I’ll post one more burble next Wednesday, and then it’s the summer holidays. I, for one, can’t wait.