Home > A Level, Curriculum, GCSE, KS3, Maths, Teaching > Stem and Leaf – is there a point?

## Stem and Leaf – is there a point?

Stem and leaf diagrams, or “Those leafy stem things”, as one of my former pupils used to call them, have long been an annoyance of mine. I’d never heard of them until I was brushing up on the GCSE syllabus ahead of my PGCE and when I did come across them I couldn’t see anything that they brought to the party that couldn’t better be shown using alternative methods.

You can imagine my feelings then as the KS3,4 and now 5 curricula jettisoned them, meaning the end was in sight for the need to teach them. I let my feelings on this be known in my recent post around the new A level curriculum and this led to further discussion around them on twitter. Then Jo Morgan (@mathsjem) wrote this fantastic piece which supports their place in a classroom and gives some great activities to use in teaching them.

It got me thinking, are my feelings unfounded? Should I be writing off stem and leaf diagrams? I’ve long been an advocate of maths for maths sake, see this defence of circle theorems for one example, so why is this feeling bot the sane for stem and leaf?

Perhaps it’s that it falls under the banner of “stats”, a very applied area of maths. This suggests that there should be an application associated with it. The use mentioned in Jo’s blog for bus and train timetables is the best example I’ve seen, but I think a normal timetable will be easier to read for the majority if people, as the majority of folk aren’t familiar with stem and leaf. Hannah (@missradders) suggested that they were used a lot in baseball, but I can’t see any reason that they would be better than a bar chart or a boxplot.

Colin Wright (@ColinTheMathmo) suggested during the twitter discussion that they could be used to build understanding around data, even though they are no use for any real data sets which would be far too big. Jo also uses this idea in her defence, saying they could provide a good introduction to the ideas of skew, quartiles and outliers. I can see this argument, but I still think there are better, more visual and less convoluted ways to introduce these to pupils, such as the aforementioned bar charts and box plots along with scattergraphs and a host of other data presentation methods (but not pie charts, they’re just as bad, if not worse! But that’s a topic for another day!)

I really enjoyed Jo’s post, if you haven’t read it I would advise you do. It made me think and look hard at my views. In the end though, I still see no need in stem and leaf diagrams and will be glad to see the back of them. If you have opinions either way I would love to hear them, especially if you have further real life uses!