## 2 November 2014

### 5 Maths Gems #12

This is going to be a relatively short gems post because I'm exhausted from entertaining 19 toddlers this afternoon at my daughter's third birthday party. So I'll be brief today, but expect a lengthier post next week when I've recovered.

1. Area of a circle (again)
In my seventh gems post I shared an applet that beautifully demonstrates how to derive the area of a circle by cutting it into sectors. This week I found a brilliant gif that shows the same thing.
This gif is taken from the animatics (animations + mathematics) section of @MathsChallenges' website. The thinking behind this method is neatly explained in Geometry: What is the intuition behind the formula for the area of a circle? which was shared this week by @GeometryDad.

2. Standard form
'The Scale of the Universe 2' is an amazing interactive resource that you could use when teaching standard index form. I originally found this resource through a recommendation made by @ColleenYoung in her post Standard Form Resources and this week @missdenzil also tweeted a link to it. If you've not seen this before, do have a look - you will love it! It allows you to zoom in and out from the tiniest things (quantum foam!) to the biggest things (the Universe). Along the way you can click on objects to see their size - measurements are given in standard form. I'd love to give my students time to explore this - perhaps for homework they could pick out ten objects (there's a lot to choose from!) and put them in size order, noting how standard form makes the sizes easy to compare.
 Extract from 'The Scale of the Universe 2'
If you're looking for more standard form resources then my resources library has some great ideas.

3. A level resources
I saw this tweet from @DrTrapezio...

so I checked this out and found that the Cambridge Mathematics Education Project is inviting schools to register as affiliates to gain early access to their free A level maths resources under development. I'm always on the look out for A level resources so I registered. There's loads of great stuff on the website and I look forward to seeing the collection develop.

Some of the CMEP's resources are now featured on NRICH. For example, the question below is brilliant (and not as hard as it looks...)

I also like the 'always, sometimes, never' card sort 'Discriminating'.

 Extract from Discriminating

And Parabella is a lovely problem for your Year 12s studying coordinate geometry.

4. Operation Countdown
A combination of ideas and creativity from @LWmathsmatters, @EJmaths and @taylorda01 led to this excellent 'Operation Countdown'. I often use the 'four threes' activity as a plenary in an order of operations lesson with Year 7 but it works with any age group. I once used it as a Year 13 starter and they really enjoyed it. The version below involves five threes but it's the same idea.
This picture is from @taylorda01@EJmaths also made this PowerPoint which includes a black and white version.

5. #units #ruler #workings
I read the post 'Hashtag closure' by @dsladkey and it got me thinking about how I could use this gimmick in my maths lessons (yes, gimmicks are ok! As long as they don't get in the way of mathematics. See my recent post 'A place for gimmicks?'). David's post is about using a hashtag to summarise a lesson.

Then @mrprcollins wrote A Frenzy of Marking: 'Progress Over Time' about feedback stickers. When I mark, I do find that I write the same thing over and over again, so stickers would save me a lot of time. Problem is, I'm not organised enough to use stickers. I do my marking in a variety of locations and normally just have a red pen to hand. Hashtags will work just as well as stickers, as long as my students understand the meaning of the hashtags.

When I mark I'm not succinct enough. For example I often write 'please go to help club at 1.30pm on Wednesday in Room 111 for help with this topic'. Instead, I could write #helpclub. I also write things like 'Look at the question - you were meant to round your answer to one significant figure'. I could just write #rounding. My students will get what I mean (especially if they have this key in their exercise books) and it will save me loads of time. "What's the point in the # symbol?" I hear you ask - well, yes, the symbol isn't essential, but #MrsMorganLikesHashtags and they're not doing any harm are they? :)

So that's it - five quick gems from a busy mathematical mum. I was planning to feature some thoughts about the value (or lack of value) of iPads in maths education today but didn't get time to do the research required, so will save that for my next gems post.

I'm also planning to write a post about circle theorems next week. I've got some ideas but if you
have an interesting way of teaching circle theorems or any amazing resources, please let me know.

Also, don't forget to check out my other website, prethomework.weebly.com - the extensive collection has grown over half-term.

I'll leave you with a base 11 abacus which I think is cute but will annoy @solvemymaths (see his post 'My Base 11 Abacus Bugbear').