Tag Archives: water

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.

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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….

Year 12 and… what?

Half term is almost with us, hurrah, and I, for one, can’t wait. Lots of sleep lined up.

Whenever I’m planning a lesson, I always like to think of the opening, the lure, the hook. After all, the students are coming in from break, from lunch, from registration, with all kinds of distractions and probably the last thing they’re thinking of is Biology. I want to grab their attention as quickly as possible, get them on task and get them thinking. Projecting an SEM image of an embryo on a pin point – what’s this a picture of? The World War 1 shell casing – anyone know what this is? And so on.

See what you think of this introduction to a Year 12 lesson.

I start by asking if any of them like crosswords. Yes, no, not really. What about cryptic crosswords? Ugh, yuck, no. OK, try this. I project the clue “Beautiful girl in crimson rose(8)”. Huh? What? Don’t get it. So I talk them through how a cryptic clue work and ask leading questions so that they eventually see why the answer is, “rebelled” (8 letters, “belle” inside “red” meaning “rose”). Lovely, elegant clue, with classic misdirection in the defining part. But where’s it going?

Then I say that I’m going to show them my favourite ever cryptic crossword clue, and that they’re going to solve it, and feel really pleased with themselves. It’s HIJKLMNO (5). Bafflement. Consternation. What the…? But they also want to know the answer, they’re intrigued. Suggestions? It’s the alphabet. What, all of it? No, only the middle bit. Describe it. 8 letters in the middle of the alphabet. Which letters? HIJKLMNO. Describe it more succinctly. It’s the bit that starts with H and ends with O. More succinctly than that….

Everyone got it? You will. And that moment of transformation, from utter bewilderment and feeling stupid to understanding the answer is great.

I then switch to the cover of “Aliens Love Underpants”. If you’ve not come across this children’s book, I’d highly recommend it. It’s based on the premise that aliens are here, among us, and they are driven by the urge to steal our underwear. It’s why you can never find a matching pair of sock and why pants go mysteriously missing. When a giant asteroid is heading for earth, the aliens, distraught at the prospect of losing their pants supply, steal a zillion pants, stitch them together in a single gigantic pair of Y-fronts, and ping the asteroid back into space using the elastic power of all that underwear.

Then I show them a picture of Earth flanked by Mars and Venus. If you were an alien, exploring a new solar system in search of a new pants supply, which planet would you choose, and why? They get it. Pants means life. You head for the blue planet, you head for the water. And there’s the key question – why is water essential for life?

I’ve attached the pictures that go with this – I’ve also attached my Water Circus and associated homework assignment. My Water Speed Dating Party, where you constantly mingle and meet a new and rather attractive molecule that you feel a definite attraction to every nano-second, I’ll leave you to imagine…

Have a great half term. I’ll be back in a couple of weeks.

Paul

Aliens love underpants

Water Circus revised Sept 2013