Interactive Chart: Diagram Representing the Mortality in the Hospitals at Scutari and Kulali, from Oct 1st 1854 to Sept 20th 1855

The activity below is the second of four produced for the University of Nottingham's Florence Nightingale Comes Home project. With another mouthful of a title, Diagram Representing the Mortality in the Hospitals at Scutari and Kulali, from Oct 1st 1854 to Sept 20th 1855 looks at death rates in Crimean military hospitals, comparing them to annual average death rates in London military hospitals for the same period.

This is a Polar Area Chart, which isn't something that comes up a lot in school maths classrooms, but there are some interesting comparisons with Pie Charts (and even Histograms) to be noticed. There's also an opportunity for discussion on the purpose of percentages, if you look closely!

Nightingale is known very well as "the Lady with the Lamp," but her contributions to mathematics are something that many people are unfortunately unaware of. She changed the face of (and attitudes towards) data visualisation in the UK, using easily understood visuals to tell the stories embedded in data that was otherwise unreadable to non-mathematicians, including politicians and royalty.

You can find the full collection of classroom resources for the Florence Nightingale at Home project at the link below:

Nightingale Classroom Resources

Want to learn more about data visualisation in statistics? Try this free course from Alison.

Sourdough Hydration

My social media feeds during the Covid-19 Pandemic lockdowns were awash with furloughed friends indulging in hobbies and pastimes, new and old. A lot of these involved some sort of cooking and baking, with two things coming out on top: banana bread and sourdough.

A jar of sourdough starter

Sourdough bread is made from fermented (which is why it's sour) dough. The fermentation process takes time, so sourdough makers traditionally use a "starter", which is a fermented mixture of flour and water. A portion of this is taken away (and mixed with other ingredients) when a new loaf is needed, with the rest of the starter forming a standby culture which is regularly "refreshed" with further additions of flour and water.

Different bakers work with different ratios of flour and water comprising their starter and refreshments. This ratio is known in the sourdough trade as "hydration" and is expressed as a percentage calculated by dividing the mass of water by the mass of flour that it is mixed with (and then multiplying by 100).

Different recipes call for different hydrations again, and these can be achieved by altering the relative amounts of flour and water in your dough. This would be easy if everyone started with the same hydration: everyone would need to add the same quantities of flour and water to achieve the same result.

Recipes on the Du's Doughs blog all assume starting from an 80% hydration starter, but blogger Erica has written a post to help those who start with other hydration values to obtain the perfect consistency for each recipe too. Read the post at the link below:

Sourdough Hydration Math

Mathematics in Work: Shop Floor Assistant

In this Cambridge Mathematics' Interviews and Intersections post, Shop Floor Assistant Neale discusses is feelings about and the place of mathematics in his work:

Intersections: Mathematics and the Shop Floor Assistant

What Do the Percentages Mean on Steep Road Warning Signs?

Maths teacher Simon Young tweeted a thread about percentages on road signs, and he's given me permission to write it up as a blog post. I've stayed faithful to Simon's original wording, with a little editing here and there, mostly based on his own corrections and some of the conversation resulting from his thread (the original thread is linked at the end).

Road steepness is expressed as a percentage on UK road signs: what does it mean, and where do the numbers come from?

Have you ever wondered what the percentages mean in those road signs about an upcoming gradient change? I know I have! Here is what I discovered...