19 July 2014

Bringing babies into a statistics lesson

I’m not particularly into babies (apart from my own little terrors darlings) but I teach at a girls’ school and the majority of my students respond rather well to baby stuff (apologies for the stereotyping). It’s surprisingly easy to feature babies in your statistics lessons if you so please. I’ve already blogged about my Bibonacci starter. There’s also this pregnant cow exam question (part d is the only S1 exam question I've ever seen which requires students to know that 68.3% of normally distributed data is within one standard deviation of the mean).

Edexcel S1 January 2002, Q5

I used this question in an S1 lesson when I was heavily pregnant, much to the amusement of my students. It led to a discussion about the gestation periods of other mammals (those poor elephants!). We’d clearly expect a fairly strong correlation between size and gestation - when I get a chance I'll see if I can design an interesting activity using this data (I wonder whether anything similar is done in biology).

Speaking of gestation periods - I remember when my due date for my first daughter came and went, I tried to find statistics online to tell me how far overdue I might go. I wanted to know the probability of baby arriving at 42 weeks. I didn’t find much online at the time but again I feel it could make for an interesting lesson.

If you are a parent then you may be familiar with ‘the red book’, which is the Personal Child Health Record issued to all babies born in the UK. This is a child's primary record of immunisations, development, health reviews and so on. At the back of the red book are the ‘UK-WHO Growth Charts’ where scatter graphs are plotted of the child’s height and weight against their age. On these scatter graphs are centile lines, to allow parents and health professionals to compare the child’s measurements against other children of the same age. On a few occasions, I’ve been asked to explain the meaning of these charts to friends with newborn babies, so it occurred to me that the growth charts could help me explain the concept of percentiles to my S1 classes.

The red book contains this description of the centile lines on the growth charts:

More information about the charts is available in this fact sheet from the RCPCH.

While I was thinking about how to design an activity for my S1 class based on these charts, I discovered that the author of The Chalk Face has beaten me to it with this nice 'Quartiles and Percentiles' activity. And @srcav has already written this blog post 'the mathematics of parenthood' about the potential to use growth charts in his teaching.

Incidentally, the red book says ‘someone who has been appropriately trained should complete the growth chart’. Hmm. I hope they're not suggesting that members of the public are incapable of adding a dot to a simple scatter graph?!

Right, my baby is awake now so I'll continue to develop these ideas another time...  Do let me know if you can think of any other baby-related data to add to my theme.

My mini-mathematicians.  July 2014.