Wednesday, 3 July 2013

Estimation. School walls - don't tell Pink Floyd!

Estimation. How many bricks?

 Pink Floyd

This is  really simple lesson on estimation that makes the topic REAL!

It is easy to do and works, plus it allows you to escape the confines of the classroom.

I guess we have all heard the song 'The wall' by Pink Floyd. I enjoyed listening to it but was never quite sure about the lyrics. 

At this time of year I think most teachers would prefer to listen to Alice Cooper, you know the song 'Schools Out'. Just to remind you about Pink Floyd’s lyric

'We don't need no education
We don't need no thought control
All in all it’s just another brick in the wall'


That started me thinking, how many bricks do you need to build a wall? How does a builder estimate the number of bricks that are needed to build a wall from the plans he or she have been given? 

A lesson began to form itself in my mind; I could use the walls of the school as a teaching resource, particularly during the hot summer days. (You can tell this was not attempted over the last few dismal summers in England.)


I posed a question to the class ‘How does a builder estimate the number of bricks required to build a wall?’ Questions were of course fired back, ’How big is the wall?’ ‘Don’t know’ I replied. 

Eventually the discussion came around to finding how many bricks are needed for a square metre. ‘How do we do that?’ I asked, ‘Well we could measure a wall’ came the reply and that is what we did. 

The discussion was also valuable because many hadn’t realised that planning was needed prior to a simple wall construction, they also did not fully appreciate the costs involved of not preparing. Life skills as well as Maths in one lesson – not bad. 

Into the sunshine

Groups of pupils, armed with metre rules, bathed in summer sunshine found the nearest available wall, marked out a metre square and started to count the bricks. 

Questions arose such as what do we do with half bricks.I allowed them to make their own decisions about that but asked them to raise the question in class. Tasked completed we went back to the classroom. 

Data collection

In the classroom I first asked what problems they had. Issues such as not being able to draw an exact square metre on the school wall and what to do with half bricks arose. 

We collected each groups data and found the mean average. Obviously it was a decimal so rounding was required. I asked did they think bricks ever got broken? If so what can we do about it? 

The idea of ordering more than you need emerged, eventually it was agreed (after some unobtrusive guidance by me) that an extra 10% was required.


Further work

From this starting point we could work out how many bricks it would take to build he wall we had just measured (I gave them my estimate of the size). 

I also provided them with the cost of the average brick, enabling further costing to take place. They them had to work out how much the bricks would cost if the wall was double skinned. 

Further extensions involved working out how mush mortar was required to build the wall. All this work could then be written up as a report.

An excellent book on prctical Maths is Mathability: Math in the Real World



The Maths involved included estimation, measuring, area, percentages, multiplication and problem solving, not bad out of a simple brick wall. I guess you do need education to build a wall.

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