## Monday, 18 February 2013

### Whole Class Stem & Leaf Diagrams

On Friday I was teaching stem and leaf diagrams to a year 10 class.

Prior to the lesson, when thinking about how I would teach them the topic, I was looking over the class' details and then something dawned on me...the seating layout looked like a back-to-back stem and leaf diagram.
The room was laid out with 4 rows of 4 tables, 2 either side of a central walkway. This then got me thinking that I could make a stem and leaf diagram out of the class themselves, with the students being the leaves and the stem being the gap between the desks in the centre of the room. However, as I didn't know how much the class had done on stem and leaf diagrams I couldn't be sure that we'd naturally get to back-to-back stem and leaf diagrams in that lesson. So, as a back up I decided I could still create a single stem and leaf diagram using the windows on one side of the room to be the stems and then the rows of desks being the leaves.

So, in order to prepare for this, I created a set of laminated numbers for each of the students. Having discussed the idea with my colleagues one of them suggested having the actual number on one side of the laminate and then the leaf part of that number on the other. This was a great addition as it then allowed the students to not only recognise what their actual number was, but also how to relate the leaf part of their number to the number itself. So, having created the number/leaf laminates I then just simply wrote each stem (0-4) onto a piece of paper and blutacked these to the windows in line with the 4 rows of desks.
I gave out the laminated numbers/leaves to the students randomly and then asked them to create the ordered stem and leaf diagram. I had the question on the IWB too for the students to refer to. The numbers all represented the ages of members of a swimming club.

What happened was great, all of the students were organising themselves (and each other) into the relevant row (stem) and then ordering themselves (the leaves). After the diagram was complete I then, to get a better view of things, stood on one of the tables and then asked the class questions about the stem and leaf. This included calculating the median, mode and range. When it got to the median I decided to take away students 1 by 1, highest and lowest until there were only 2 students left in the middle of the diagram; I linked this to when we cross off from a list of ordered numbers until you get to the middle number/s. We then discussed what the median would be of the two numbers left over; there were some misconceptions here that we were then able to cover.

The activity worked really well and I will do a similar thing in the future when we look at back-to-back stem and leaf diagrams.