# Re-arranging formulae lesson

Discussion in 'Mathematics' started by scentless_apprentice, Mar 4, 2012.

1. ### scentless_apprentice

Hi all,

I'm after a bit of advice for a lesson observation in the form of an OFSTED inspection (oh yes) and I want to try something out regards the format of the lesson.

It's going to be on rearranging formulae, and within 20 minutes I want to be able to tick all the boxes re progress, differenation, AfL, etc etc.

From the off, I'm going to try and do very little explanation myself. I'm going to give the students a set of formulae, and some rearrangements - some correct, some not.

I'm going to go through each one and ask them to explain to me why they're right or wrong, and then if they're wrong, get the students to show their answers to me on whiteboards. I'll then get the students to go through an explanation if they're right.

Then I'm going to get them to have a go, in pairs, at matching a set of formulae with their rearrangements. There'll be a choice of two sets, one harder than the other. Students can pick what they want to do.

Then I'll display the answers and get students to mark their own.

For the plenary, I was going to do a simple 'show me' task where I put a formula on the board and they show me a rearrangement.

What do you reckon? Is there any way I can tweak this? Am I planning too much? Is it too dry?

It's a big ask but I'm going for it to get SLT off my case and give my department some ideas on this.

2. ### PaulDGOccasional commenter

So what are they learning?

If they can do/understand the examples you've given them, how are they progressing?

If they can't do them, what are you going to do when they start throwing things around and get their phones out?

Go back to the basics. What do you want them to learn?

3. ### MasterMaths

My first thought is that it if you look at what you want them to be able to do at the beginning, the middle and then end ... I'm not sure there really is much progression.
Unless, of course, you mean you will start with a = 2b and rearrange to b = a/2 and then end up with something much more complicated?
Also ... I quite like giving the whole class a formula and three potential rearrangements to choose from. 1 is obviously right, whilst the other 2 are wrong (normally highlighting common mistakes around brackets, +/-, order or ops or powers). The class then have 60 seconds (or whatever) to work out the correct one and right A, B or C on their mini whiteboards before you ask everyone to hold them all up. Quite similar to one of your suggestions, but just changed slightly.

4. ### scentless_apprentice

I want them to be able to rearrange formulae with brackets, powers and roots in them.

I understand what you're saying, but by doing the initial exercise I hope to understand what they know, and what they don't - they're going to show me if they think the answer is right or wrong using the whiteboards, and then I'll ask them to take me through their decision making.

I'm planning to keep the pace quite high so they're not spending ages on the simple a = 2b style formulae.

All this is good stuff so far, thankyou.

5. ### PaulDGOccasional commenter

Is this a class you know? Do you expect them to be able to do basic rearrangement? Can they make b the subject of c = a + b ? How about c = a * b?

(In year 10 & 11, your science department is almost certainly using tricks like writing V = IR in a pyramid and "covering one up" to find the rearrangement. Does your class need that sort of support?)

Also, does your department have a policy on the method to be used for rearranging? "Story of x?", "Balance method?" and the layout expected?

Where are they now?

Where do you expect them to be by the end of your segment?

How will you get them there?

How will you know they're there?

6. ### PaulDGOccasional commenter

Rearranging roots.. That's something top set year 11s fall over at.

Is this a top set? Very able?

If so, they won't like playing Ofsted games - they want "the maths" so they can know what's expected and show you they can do it.

If it's not a top set, then rearranging with square roots is perhaps not the best thing to go for in an observed lesson - even as an extension, it's likely to raise a lot of questions and leave the lesson in chaos for a while.

7. ### KarvolOccasional commenter

And there you have UK teaching philosophy encapsulated in a couple of sentences.
This is not a dig at the OP, but surely the teaching of mathematics comes first and everything else is a by product?

8. ### scentless_apprentice

Hi Karvol. Yes, absolutely, I 100% agree with you. This exercise really is so that I can find out a) what's really expected to get Oustanding these days and b) if it's sustainable.

I am not relishing the prospect of this at all, and it's not something that I want to become the norm.

9. ### AnonymousNew commenter

Is outstanding sustainable? Good question.
I have found when rearranging equations that children struggle with
3x+ wx = 25
Then factorising out x
x (3+w) = 25
x = 25 / (3+w)
They struggle to see that factorising step - unless it is shown to them. Then hopefully they can apply it next time.