Category Archives: Number

135. Book (& Website) of the week 2

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If you are on Twitter, you may have heard of the perfectly titled @MathsBookClub. If not, let me explain.

People were asked to nominate their favourite Maths related book (Fiction or Fact).

People voted and the most popular was chosen.

The winner was: ‘Alex’s Adventures in Numberland’ (‘Here’s looking at Euclid’ USA) by Alex Bellos.

Just like a “meet down the pub bookclub” there will be an online discussion on Wednesday 23rd October. Except with this bookclub, the author has offered to join in! Very cool!

To join in the mathematical literary fun either follow @MathsBookClub on twitter, visit the mathsbookclub website or do both!

(Support your local Library. If that’s not possible then click on the book for a link to the paper version on Amazon.co.uk; ebook also available)

131. App of the Day: MyScript calculator

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A short post today. This week J introduced me to the ‘MyScript Calculator’ app.

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It’s a rather nifty app that converts freehand writing into mathematical calculations and solves them. It is available for most formats of smartphone and you can visit their website here.

These examples from the website show what it is capable of doing – I’m sure there is a lesson here somewhere.

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128. Book of the Week 1

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If you haven’t had a chance to take part in the rather excellent ‘How to Learn Maths’ online course at Stanford University, led by Jo Boaler – don’t worry!

 

Get reading the rather brilliant book ‘The Elephant in the Classroom’ instead. You’ll find yourself going ‘Yes, I know what you mean!’, ‘I’d never thought of that …’ and ‘I need to try this out’, before you’ve even finished it.

 

127. How to save money

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A nice easy question to start the term with:

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You go to the supermarket to buy your favourite shower gel (or other product). It usually costs £2.99. You have three £1 coins ready, when you notice the price has temporarily been reduced to £1.

What is the most money you can save?

Hint: Think of future gain

Solution:
It’s not the obvious £1.99 saved – that is instant gratification.

It is actually better to buy 3 bottles:

Saving = Actual price x 3 – Reduced price x 3

Saving = £2.99 x 3 – £1 x 3 = £8.97 – £3 = £5.97

If you spent the whole £3 (which is one bottle plus one pence), you get a long term saving which is worth far more, for just 1p more.

Teaching the concept of delayed benefit is rather useful, especially if you are trying to encourage open investigations or looking at time spent on personal revision.

118. App of the day

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Do you ever play the numbers round from the TV programme ‘Countdown’ in class?

I was on a training course the other week and whilst chatting in a break Sarah – a fellow delegate, introduced me to the free android Countdown app. It is so easy to use a 6 yr could (and does) use it.

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There are quick rounds, full games and practice mode. If you choose the number practice mode, you can randomly select numbers and it will even show you the solution. So you can use Countdown as a starter without scribbling numbers on a bit of paper and only being 10 seconds ahead of the class.

Download it from the android store by searching for ‘Countdown for Android’.

117. Circle facts

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I sometimes despair when I read through students’ exercise books. A brilliant explanation or set of revision notes are let down by poor diagrams – especially when you are working on circle theorems. I’m also suspicious of handing out perfectly typed notes because I’m sure they don’t get properly read.

I’ve taken both these issues and put together a C grade Circle Theorems Fact finder sheet. The diagrams are printed, but the theories are missing. Students need to write the missing facts in their own words. This processing of information should consolidate their understanding.

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Download it from here.

115. Decimate

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Here’s a nice (gory) problem to use as a plenary.

What does the word ‘Decimate’ or ‘Decimation’ mean?

The word derives from Latin meaning ‘to remove one tenth’.

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The original context is the punishment of a Roman Legion. The unit was divided into groups of ten and lots were drawn. The unlucky soldier was executed. A Cohort consisted of  480-500 soldiers, a Legion consisted of 10000 soldiers. How many would survive in a Cohort? How many would be executed in a Legion?

Now if the class were an unruly unit, how many would draw an unlucky lot?

A legend suggests that the Theban Legion was decimated in the third century AD. The Legion had refused, to a man, to accede to an order of the Emperor, and the process was repeated until none were left. They became known as the Martyrs of Agaunum (there are several sources on this).

Rather than execute your class I use this legend as a logic problem. Which pupil in the class is safe? Either the class stands, sitting when they are ‘executed’ or stand and then line up to leave. You can stop every few counts and ask who thinks they are safe. Last soldier standing leaves the lesson first!

Don’t have nightmares!