Year 10 respiration.
I’m not teaching KS4 at the moment, so I’m not really thinking about Year 9-11 lessons these days. But when a colleague told me what she’d been doing with her Year 10s, I just had to report it here. Her approach was brilliantly simple.
So, she said to the class, what’s the equation for aerobic respiration?
They dutifully parroted the glucose plus oxygen goes to carbon dioxide and water routine.
And respiration is one of the….?
(parrot): Life processes.
So it only occurs in….?
(parrot): Living things (like parrots).
And then she socked it to them.
How do you know?
How do you know?
(hesitant). Because you told us?
But why believe me? Just because I’m a teacher? An authority figure? That’s not how science works!
Pause for effect….
Go on, prove the statement. Living things take glucose and oxygen and produce carbon dioxide and water. Show me that it’s true.
And that was it. She didn’t tell them how. She didn’t give them a method or a plan. She just provided standard lab apparatus plus a few other things, including methylene blue, balloons, lime water and yeast in suspension.
It was joyous. Set free from the constraints of a set protocol, they threw themselves into the problem and solved it in a variety of ingenious ways.
I’ll post photographs of their results as soon as I have some, but it was one of those lessons where you wish an Inspector had just happened to drop into.
Year 12 Immunology
Burble follower Nicola has asked how I start Immunology with Year 12.
I base most of my Immunology teaching on Lauren Sompayrac’s brilliant book, How the Immune System Works – indeed, I shamelessly steal most of his ideas and analogies, including this one.
It’s a lesson that is largely chalk and talk – though with lots of opportunity for questions and discussion. It’s such an inherently interesting topic that they stay focussed throughout. I always try and push the detail as far as possible, because it is so much more beautifully elaborate and complicated and sophisticated than they can possibly imagine. I also like to characterise the cells – macrophages as the general garbage collectors who can be upgraded to vicious killers. The visigoth neutrophils who just “kill things and break stuff”.
So I ask the students to compare their body to a fortress, or castle. How will they keep out the invading barbarian forces?
So they get the idea of a huge perimeter defended by an impenetrable wall (skin).
But there have to be gaps in the wall to allow supplies into and out of the castle (digestive/respiratory/reproductive systems) – and compare 2m2 of skin with 400m2 of mucus membranes!
How to defend this?
So the idea of more basic defences – boiling oil perhaps representing mucus, acid, lysozyme, earwax….
But what happens when there’s a break in the perimeter barrier? A trebuchet bashes a hole in the wall, you cut yourself…
So we talk about the impossibility of defending every inch of the perimeter with sufficient forces. What would you want instead?
They quickly suggest sentries. Aha, meet the macrophages. Patrolling the tissues.
And when the perimeter is broken, what would you want a good sentry to do?
Send for back up! And fight the invaders until help arrives.
Sending for back up allows us to review/revise cytokines and cell signalling.
And with the back up you’re talking about the 20,000,000,000 neutrophils circulating in the blood. Why is it a good idea for them to circulate in the blood? I describe the slow, sniff, roll, exit behaviour of neutrophils in response to macrophage cytokines. It’s just all so cool!!!!
I tell them about the biggest ball of pus I ever saw, rolling slowly down the shin of my then girlfriend Louise, following an infected mosquito bite in Uganda. A huge ball of… dead neutrophils. Why is it important for neutrophils to be short lived?
And so on.
I’ve attached my PP illustrating antigen presentation Immune response (imagine that lymph glands are singles bars with 1000s of lonely B-cells being constantly introduced to potential antigens, hoping to meet their perfect match..) and clonal selection/expansion. Bit primitive, but it works. And my exercise for them to annotate and explain.clonal expansion summary
Hope this helps!
PS don’t forget to talk about breast feeding and the importance of kissing your baby! the idea that you sample the antigens around your baby’s mouth, quickly make the relevant antibodies, and ship them into the breast milk will astonish, amaze and intrigue them.Natural Passive Immunity mum’s milk