When I was sifting through my resources to plan a lesson on composite shapes I came across a question from a previous UKMT Junior Challenge. I decided to use this question as a plenary with my Y8 class. When thinking about how to best use the question as a plenary I decided to get the class to use 'post it notes' to indicate to me the answer they believed to be true.
Here's what I did...
I gave each student a post-it note and told them to put their name on it. I then, on my whiteboard, wrote the letters A-E, split into 5 separate columns. On my IWB I then displayed the question to the class and told them that I would read the question out to them, give them a bit of time to think about it, then, when they had an answer, they'd come up to the board and place their named 'post it note' on the board under the letter's column they believed to be true. After reading the question, I gave the class a bit more support by drawing a diagram of the 6 by 8 and 7 by 9 rectangles and then, using SMART notebook, dragged them over the top of one another to create the overlapping shape in the given question. This was a really good visual representation of the problem and soon allowed students to start noticing the dimensions of the shaded areas to work out (see image below).
I was really impressed with how the class responded to the task and praised them for attempting, and doing so well, on a challenging question (I told them about the UKMT Junior Challenge and how we, as a school, usually only enter our set 1 students in KS3 [my Y8 class are set 3 of 4]).
Here was the end result...
Another great thing about this...the answer was 27! My Y8s thought I had designed the question myself, I had no idea until I checked it through when planning the lesson - a wonderful coincidence (especially having just introduced them to my 'twenty seven' takeaway homework - see http://goo.gl/s6YAln).
When reflecting on the usefulness of the task as a plenary and assessing where my students got to, the one downside I could see, was the potential for students who had no idea to follow the crowd and just place their post-it where everyone else did. Not sure how best to avoid this in future...answers on a postcard please (or in a tweet @mrprcollins)