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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5 thoughts on “The Lesson from the Black Lagoon….

  1. Melissa

    Weird, tomorrow I start teaching elements and atoms with 3 year 8 classes. I shall give this activity a go, probably only the brighter students will get it, but they can have a go at explaining it to the rest that don’t. Just a quick question re valence, did your kids know about atomic structure beforehand? Do you discuss valence at year 7 in the UK????

    I love teaching junior science. I have 4 year 7 class – they’re (mostly) adorable. They still think science is cool. Melissa.

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    1. paulweeks2014 Post author

      Hi Melissa! No, this was the follow up lesson to their introduction to elements. They had done nothing on atomic structure. They obviously wanted to know what valency meant, so I talked about atoms having arms for connecting to other atoms – we did some role play later where oxygen students held hands with hydrogen students – hence H2O – which they liked. Let me know how it goes! If you think they’ll need more help, suggest they put them in sequence and look for patterns…

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  2. Andrew de Salis

    You can’t beat creative teaching. Sounds like your kids learned some real science, and had a great time doing it. Please keep posting.

    ( Next week I’m making my debut as a Year 7 and 8 Maths teacher, covering a colleague’s absence for a couple of weeks. You can stop laughing now. )

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