# Intersections: maths and the plasterer

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- Intersections: maths and the plasterer

## Intersections: maths and the plasterer

**Edward Evans is a plasterer working in Hertfordshire.
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**How would you characterise your current work? **

I am a self employed plasterer and a sub-contractor for other builders and householders. I work by myself. Most of my work is plastering extensions by measuring and cutting plaster board, and fixing to walls or ceilings. I also do floor screeding, which is mixing sand and cement and spreading it on the floors to make a level surface.

**How do you feel about maths? **

Maths I use as a tool just like a hammer or a screwdriver.

**What is it about your work that is mathematical? **

The most mathematical thing I do is measuring, for example considering boards on walls and then cutting them to size. I have to very carefully work out how much board I need. The standard size boards I use are 2.4m by 1.2m by 12.5mm thick. With floors, I have to measure how much sand and cement I need, and also take into account if insulation is needed under the floor.

**How do you use maths, calculation or numeracy in your work? What tools do you use to help you? **

I use maths for calculating: one example might be for volume of floor screed needed, i.e a specific mixture of sand and cement. If the room is 4m long by 3m wide and the floor needs to be at a depth of 0.100m, I multiply all three together to get 1.2m^{3}. I use a tape measure for measuring length, width and depth.

**Do you think maths is creative? If so, how? **

I think decorative geometry is the most creative type of maths: circles cutting into circles into an expanding flower shape (often known as the flower of life, see image below). I’m also fascinated by the fact that the Pyramids were built with the golden ratio of 1.6180. I think maths can help give an answer to why some proportions intuitively look right and others don't.

**Do you use or rely on any maths that you learnt in school? **

I do use some of the maths I have learnt at school, but this is only the basic stuff. I've forgotten most of it as what I do day-to-day feels different and out of context compared to the maths in the classroom. The maths I use in the work place has become automated, like second nature, and is interestingly often not using the same method I learnt at school.

The picture below shows a triangle of plasterboard which is made to fit in a triangular gap on a ceiling.

On the bottom edge I would measure the length from corner to corner, find the middle, then using a 90 degree square measure up and mark a line going up to the height of the top edge. For example one side measured 90mm, the other 60mm from that centre marking. Then I would measure out the lengths of the edges to double check that it would fit.

**How would you change the school curriculum, if you had the chance? Why?**

I think it might help if there were more physical representations of the mathematics available i.e. physical squares, circles, triangles, pyramids etc. maybe with measures on them, like lengths of sides. I also think many more real world examples would be useful, like ‘how you could survive at sea by dividing up the drinking water which you had to live on?’ or ‘if all of the money in the world was divided by the population how much would each person have?’ I would have loved to have been able to consider in a maths lesson how astounding it is for us sitting on a spinning ball at 1039 mph at the equator, spinning 66,500 mph around the sun whilst simultaneously going half a million mph round the Milky Way.