Monthly Archives: April 2016

Introductions

First, a very quick quick word on the Year 8 Wheat and Weeds experiment. Well, they really enjoyed the freedom and autonomy of designing their own way of answering the question. 8 different group, 8 different approaches – but all highlighting an understanding of controls, measurements, repeats…. with no input from me other than posing the question and providing the apparatus. The contrast between a class dutifully following a series of instructions, and a class where individuals work it out for themselves, couldn’t be starker. So I was pleased with that bit…

…stay tuned to see if they actually get any results…!

I’ve burbled before on the importance of how you start a lesson. Some way to grab their attention, spark their curiosity or imagination, get them thinking…

Two examples from the last week.

Example 1

Biotechnology with Year 13. Immobilised enzymes. NB if you don’t do this practical…

Immobilised enzymes

…put it to the top of your priority list for New Things I Will Do Next Year – it’s a 24 carat guaranteed gold medal winner – students are utterly delighted with the little alginate beads of entrapped enzyme, and, better still, it works 100% reliably – starch is successfully hydrolysed to detectable levels of reducing sugar – (let me know if you need the technical details…).

I’ve done this for years, but wanted a slightly different beginning, partly just for a change, partly to try and emphasize/clarify a couple of the learning points.

So I gather them around my demonstration bench.

There’s a couple of cobs of maize, a bottle of amylase, and some random labels from Ready Food packages.

What’s the connection between these objects?

It’s an interesting reaction. Students used to me start passing the things around, reading the label on the bottle, looking closely at the food packaging. Students new to me, more used to being spoon-fed the answers, wait patiently to be told what to think.

But even the willing ones get a bit stuck, so it’s time for a hint (always hint, never tell them: always answer questions with questions – they need to work out the answer for themselves, even if they need a bit of help to get there). Read the food label really closely, I suggest.

Which they do. A couple of them spot it simultaneously. “Modified maize starch!” (it’s great, isn’t it? The equivalent of “aqua” on shampoo ingredients).

OK, so what’s the link?

And so we talk about maize being a great source of sugar because it’s so rich in starch. And can be grown in temperate countries. And that starch can be readily hydrolysed by the enzymes that your genetically modified bacteria produce in such vast amounts (which leads to an interesting side issue on another label on the product – “Contains no GMOs…”). And why enzymes are so attractive to industry. But how a big pot of starch + amylase negates two of these attractions – the ability to re-use them and the purity of the product…

… which leads perfectly into their Immobilised Enzyme procedure.

Example 2

Elements, Mixtures and Compounds with Year 7. I’ve already described the second lesson in this SoW at exactly this time last year – see The Lesson from the Black Lagoon – 28th April 2015 – but just had an additional idea for introducing the topic itself. I don’t think this is particularly brilliant or original (I imagine most Science/Chemistry teachers do something similar), but it certainly got them thinking.

Time to project a picture.

Democritus-400

Who’s this?

Of course, they have no idea. Never mind. He was Democritus. Ancient Greek. Ancient Greeks didn’t do experiments, but boy did they like thinking. I produce a bit of lead and a pair of scissors. And cut the lead in half. And cut it in half. And cut it in half. Can I keep doing this? Forever? Assuming very very sharp scissors and very very good eyesight, is lead infinitely divisible?

The thought definitely grabs them and sparks discussion. Yes, say some. No, say others.

I tell them that Democritus was in the No camp. And coined the word “Atomos” – indivisible. They like this – they’ve heard of atoms and now they know where the word comes from.

A clump of molymods seals the deal. Look – imagine these are atoms of lead. In a clump of lead. I can divide them. And divide them. Until I’m left with… and they see the final, indivisible atom.

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Sowing discord

Hello! Back again after a really splendidly wonderful 3 week holiday.Hope you all had a great Easter too.

Refreshed and energised? Raring to go? Bubbling and, indeed, burbling with enthusiasm? Hmmm, not sure about any of that. However, I have been pondering potential burble-topics, and find myself returning, again, to my KS3 project and the latest new topic with the Year 8s.

And here’s an activity from the opening lesson of the OLD SoW. I need to emphasize that it’s from the OLD SoW as I want to use it as an illustration of how and why I set about revising something.

Here it is, word for word. Remember – this is for a Year 8 class. Remember, too, that in the old SoW, there would have been one tray between 29 students.

INVESTIGATING COMPETITION BETWEEN SPECIES
You are going to investigate the effect of weeds on crop yield.
Divide a seed tray in two. In one half you are going to sow wheat seeds only. In the other half, you are going to sow the same number of wheat seeds and also some cress seeds (being used as weeds). After 4 weeks you will harvest the wheat; find the total mass of wheat harvested from each of your two crops, and compare these two masses.
Input variable
Outcome variable
Controlled variable
Prediction
Say which of the two crops you expect to have the larger mass of wheat when it is harvested. Remember to use the word “because” in your prediction, try to give a biological explanation for your prediction.

There then follows a detailed, 8 point method detailing exactly what they have to do, a results table and some heavily guided questions, which I have neither energy nor inclination to repeat here, finishing up with this drearily uninspiring homework, :

You are a government agricultural adviser. Write a letter to a farmer, giving advice about weeding his crop.

Well, I don’t know what you think, but my first reaction is to chuck this in the bin. There’s just so many things horribly wrong about it. Here’s a short list:

  1. Students have no control over what they do – they simply parrot a methodology. They have no ownership – and therefore no interest – in the experiment or in the results.
  2. There’s no real investigation here – students are told what to expect, told exactly what to do, and told what to write for their explanation. It’s not science.
  3. The learning outcomes are very limited – perhaps the best you could say about it is that you find out if your students can follow written instructions.
  4. And one tray for a whole class! I know teachers often like to be in control, but that’s just ridiculous. At any one time, 90% of the class will not have anything to do, except ponder what the input variable is. Like they’ll care.
  5. To add insult to injury, the sheet just looked horrible – a tiny, unreadable font spread over two pages. It was tired, faded, unattractive, not a single picture, photocopied 1000 times and never revised or updated or even just smartened up. Why should students care about a lesson if you can’t be bothered to make the resources look nice?
  6. In short, Ugh.

But having spent much of the Easter holidays on my hands and knees, digging up the ground elder that is threatening to engulf our raspberry plants (and forming a very healthy respect for this splendidly robust and devious weed), I wondered if something could be salvaged.

After all, the actual experimental set up is quite neat – and as I’ve said before, students may hate learning about plants, but they absolutely love growing them – the daily miracle of seeds giving rise to fresh green growth certainly moves them at some profound level, even if they would never admit it. As always, the trick is just to adjust the focus and structure of what they do, so that it becomes like real science, and so that they learn by doing.

Once I had decided that, the rest was easy. Here’s the new sheet with the new lesson plan.

Weeds vs Wheat

As you can see, in the new version of this activity, pairs of students get a tray between themselves. They will have to design and carry out an investigation on the effect of weeds on a crop plant. The experiment needs to be controlled and generate a measurable outcome, but after that they’re on their own. I will supply wheat seeds and a variety of weeds to choose from –  cress, yes, but also ground elder, bind weed, maybe some creeping buttercup…. – but they’re free to bring in their own. Dandelion seeds? Stinging nettles? The experimental design is entirely up to them.

I’ll let you know how it goes!

Ah, the sun is shining, it feels like Spring is finally here. Have a good week.