## Saturday, 1 December 2012

### Stem & Leaf Birthday Diagram

Having been tweeted by @209fifashirts (Nick Warrick) about whether or not I used a Stem & Leaf Diagram to display my form group's birthdays I decided to take his suggestion and do one for my set 5 year 8 classes (I have both sides of the year group).

I wasn't planning on teaching this to either groups but thought it'd be nice to give them an insight into what they were and how they worked nonetheless. So, on post it notes I got them to write the day of their birth and had pre-prepared the stem to my diagram on the display board at the back of the class. The class were then asked where their post-it should go. Some of them intuitively realised that the 01, 02, 03, ..., 12 represented the months of the year and so placed their note next to the correct stem.

I then asked them a series of questions when all notes had been stuck next to the relevant month. I asked them what the range of their birthdays was, who's birthday was the median birthday, whether there was a mode birthday (there was for one of the months). I also explained what the 'stem' and 'leaf' parts of the diagrams meant, the fact the the 'leaf' had to be in order so we could tell who's birthday was first etc. When both classes had done an individual stem and leaf diagram I then created a back-to-back stem and leaf in order to compare the two classes with each other. As I am lucky to have only 10 students in each class it was a clear comparison in terms of the numbers of students represented in each. I was also represented in each one and so this also provided a frame of reference for each one.
Again, I asked more questions in terms of which class had more birthdays in certain months, how many people's birthdays came before mine in each class etc.

Here's how the display looks up in class now...

I have used Mr Barton's revision notes to add a more 'realistic' explanation of stem and leaf diagrams for the benefit of my higher sets in KS3 and KS4 to look at.

The green post-it notes are from www.magicwhiteboard.co.uk and stick to the wall without the need for glue or staples etc. The sticky notes are also reusable and can be written on, rubbed off and then written on again many times! I have used a load of their products for my class displays and highly recommend them.