Monthly Archives: April 2015

The Lesson from the Black Lagoon….

As I’ve mentioned in previous burbles, one of my main projects this year has been to overhaul the KS3 scheme of work for the Year 7s (next year I hope to tackle the Year 8s). This has been a mammoth undertaking, far more work than I had originally envisaged, but has also been a huge amount of fun; I’ve loved teaching Year 7s for the first time in my career, and I’ve loved the creative aspect of creating new lesson plans and resources. Because KS3 Science is standardised across the year groups, it’s also been my cunning way of ensuring that this investigative approach is used by other teachers…

But at this time of year, with 6th form rapidly approaching study leave and PSAs to deliver, mark and moderate, and all kinds of other time consuming priorities, I had decided to leave any updating of the Element and Compounds topic until next year. And then I saw the first lesson on the olde scheme of work…

“Give out the packs with the periodic tables: discuss the periodic table and elements – what they represent and a basic idea of how they’re organised. Make sure students write down the definition of an element.”

… and I thought, I’m not doing that. No way. I can’t imagine a worse way of doing this. Sure, they have the information. They’ve written something down. But having a pack of information, writing something down, is not the same as knowing something. And knowing something is not the same as understanding it. And, worst of all, however you dress it up, it’s just dull dull dull. The lesson from the black lagoon.

So we did this.

After an introductory practical “circus” of elements and their properties, which I hadn’t changed from the original SoW, and which they got very excited about, (especially when they got to test the gas jar for the presence of oxygen to see whether the label was accurate, or whether I was lying), I talked a little bit about the history of elemental discovery. All these elements! All these properties!

Then I gave each pair one of these with some scissors

Periodic table cards for working it out a la Mendeleyev

a set of the first 20 element cards in the order that they were discovered. The cards had the atomic number (which I just called “weight”), the valency, and a brief description of the properties. They had to cut them out and try various ways of arranging the cards to see if anything interesting emerged. They were not allowed to do any research – they were not allowed to look at the Periodic Table in their planners. This prompted lots of good questions – what is valency? What do I mean by “weight”? And so on.

At this point it got quite full on. Some put them into piles based on their state of matter. But this didn’t really show anything interesting. What else could they do? Don’t put them into piles, for a start. Arrange all the cards face up and visible on the desk. They tried grouping them by valency, and although that saw the Noble Gases pop out in a nice, distinct collection, it also saw Sodium in with Chlorine. Not helpful. What else could they do? What would be the simplest thing to do?

I was rushing from group to group thinking, next time, they’ll do it in 4s, not pairs!

But then they started to crack it. They starting putting them in order of weight and, joy of joys, they started seeing it. And they got VERY excited. Look! These ones have all the same properties! And so do these! And these! Look! The valency goes 0, 1, 2, 3, 4, 3, 2, 1….

What’s going on????? It was one of those glorious, eureka moments that make teaching better than any other job on the planet.

At this point I talked about Mendeleev. How he had an element named after him. How he transformed our understanding of Chemistry. How he was a genius. And how they had just done exactly what he did.

And there was something else he did, too.

I then handed out these

Periodic Table with gaps for predicting properties

Periodic Tables with 3 elements blanked out. Tell me about these elements, I said. You don’t know what they are, you’ve probably never heard of them, but you can still tell me something about them. At first they weren’t quite sure what I meant. Did I want them to find out the names? No, I don’t want you to do any research. I don’t want you to find out anything. Just tell me something about those elements.

And then they twigged. Element number 1, must be a soft metal that reacts readily with water and has a valency of 1. Element number 2 must be a coloured, poisonous gas with a valency of 1. Element number 3 must be a colourless, odourless, completely unreactive gas with a valency of 0. Bingo! Meet rubidium, bromine and krypton.

There are things I’ll change the next time I do it, but as an exercise, it works. They figure it out, they understand it, they can use it to make predictions… next time, we might write some of it down…

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Approaching the Genome

Back in school after the Easter break and what a difference in the 6th form students. They were utterly spent at the end of last term, pale, shattered and weary of school. But now, well rested and with study leave less than 3 weeks away (for the Year 12s) and 5 weeks away (for the Year 13s), they’re positively bouncy, focussed, enthusiastic, energetic and raring to go.

The Year 13s are covering genome sequencing – how it’s done and why it’s interesting. This astonishing image

genome lollipops

shows all the currently identified risk factors for 17 types of trait at specific locations on each chromosome. It’s an attention grabbing start to the topic. Quite apart from anything else, how on earth would you set about finding all that out? What information do you need? The idea of sampling and comparing the alleles and other variants of more than 500,000 loci for thousands of people, some sick, some healthy, and looking for significant associations, is a bit of contrast to Chi2. It’s also clear why super-computers are vital for crunching the data and processing the stats….

We discuss the possible applications of this amazingly powerful information. One particular base sequence on chromosome 16 can contribute 3 to 4 extra kg of body mass. Then there’s Angelina Jolie and what she did with her knowledge of the BRCA genes. And just why are there so many conditions associated with Chromosome 6…? (where the MHC genes reside).

Then it’s time to figure out the technique, as stipulated by OCR. This resource The Enigma Code generally goes down well, though one girl did mutter this year, as her partner said brightly, “I wonder what the secret message is?” – “oh, it’ll be some lame joke.” How well they know me. This follow up, looking at the use of overlap, is also helpful Return of the Gene Sequencer.

But one of the things I really enjoy about working in Oxford, is that you get a real sense of how quickly Biology is changing and advancing. One girl, handing in her poster summarising automated Sanger sequencing http://www.dnalc.org/resources/animations/cycseq.html , reports, “my dad says that no-one does it like this anymore,” which provides the obvious response, “Don’t they? Right! Let’s find out what they do do…” though subsequently trying to get our collective heads around Nanopore sequencing was of limited success. Nowhere else does the specification lag so far behind developments in the real world!

Another girl reports that her father is associated with a company called 23andme and, joy of the information age, we can instantly access it in the lesson. https://www.23andme.com/en-gb/ Wow. This looks amazing! I’m wondering if I can wangle some dept. money to have a demonstration report on, say, me… for educational purposes, obviously. I already know I’m not a carrier for cystic fibrosis, but given my high consumption of espresso, it would be interesting to assess my ability to metabolise caffeine…

At £125 a pop, we obviously can’t do all the A-level students but they’re pretty happy to amplify part of their PTC receptor gene to identify their genotype and see how it links to their phenotype (this resource from Carolina Biological is superb http://www.carolina.com/human-genetics/using-a-single-nucleotide-polymorphism-snp-to-predict-bitter-tasting-ability-kit/FAM_211376.pr?catId=10141&mCat=10101&sCat=10138&ssCat=&trail=7002:10421&question= ). I’ve invested heavily in all kinds of genetic kit in recent years and it’s been worth every penny. What could be more exciting than not only extracting your own DNA, but then amplifying and analysing it? They love the equipment – using a micro-pipette never gets stale – and are fascinated by the procedure. All good stuff.

Back to PSA marking and invigilating. Next week I’ll report on how the Year 10s got on with fruit fly breeding and whether they managed to figure out the Mendelian laws of inheritance from first principle…