median
don steward
mathematics teaching 10 ~ 16

## Wednesday, 13 July 2016

• wheelchair ramps
• roof pitches
• pyramid inclinations
mainly useful to introduce arc tan (rise / run) to obtain the angle of inclination

### ratio presentation

the ratio slides
Prince's Trust (PTI) presentation
London 12/7/2016

## Sunday, 3 July 2016

### factors of numbers and number of factors

once the prime number decomposition of a number has been identified, there are reasonably straightforward rules for deciding how many factors a number has

using facts such as a prime cubed has four factors

the powerpoint for this

## Thursday, 30 June 2016

these are based on the symmetrical arrangements for the Zygolex (word linking) puzzles

in these problems the centre expression can only be changed by one of the four allowable steps at each stage, to (eventually) reach the outer expressions

there should not be any repeated expressions in the solution

work out what the allowable steps must be first

## Wednesday, 29 June 2016

### directed number target

deliberately designed so that there at least two possible solutions

the powerpoint goes into ( fairly ridiculous) detail about possible generalisations

### find the linear rule

given 7 points that fit a (linear) rule
but 2 of them are incorrect
from an idea by David Wells

plotting them seems to be cheating...
putting them in order eminently sensible

the powerpoint goes through a couple of examples

### a quadratic meets a linear family

practice in factorising a quadratic when 'a' is not 1

a generalisation can be explored
and proved
('put a pattern in and you'll get a pattern out' David Wells)

### slopes of hills

the powerpoint has some pics of steep hills, mostly in the UK

the Gloucestershire cheese rolling annual event was introduced to me by Darren (thanks to him)

tackling, a bit anyway, a difference between sinA (usual on signs) and tanA measures

### circular perimeter

this problem is from David Wells' collection in 'curious and interesting geometry'
does the line always bisect the perimeter?

the powerpoint goes through a special case and the general case

is presented with animation on the slide

### dividing by 7

the powerpoint shows some of the divisions
and makes links to the recurring decimal form of 1/7th
(including some at an advanced level - using the sum to infinity of a geometric series)

plenty of practice with the 7 times table

### that's curious

the powerpoint involves
• decimals
• directed numbers
• fractions
sometimes the relationship does hold even though it usually doesn't

## Tuesday, 28 June 2016

### polyhedra: total angle sum

Euler's relationship connecting the numbers of faces, edges and vertices (F + V is close to E) for polyhedra is fairly well known

another (very neat) relationship for the 'total angle sum' was brought to my attention by Gordon Haigh, when he worked at Wolverhampton University

a powerpoint for this task gives the steps for proofs for a general prism and general pyramid, establishing Euler's  relationship for these polyhedra

animated platonic solids from Wikipedia: