NBFs: “What’s The Chance Of That?”

The end of the school year is hurtling towards us at an astonishing pace. My grade 12s/seniors/final year students will sit their IB Diploma exams in the first week of May, and I’m excited for them, but that’s another blog post.

Although my head swims with my grade 12s who I refer to as “my babies”, this post is about my grade 8s and their probability unit. We are pressed for time so how to get it all in was a challenge. Every year we have a casino night and to not do it would upset students and parents. The solution was not to teach the content prior to tasks, just start investigating (with some scaffolding). We started with an investigation called “What kind of gambler are you?”. NCTM has a great activity called SKUNK and we MYPed it.

Before I begin I will digress a little, again, and say stick with this post until the end. The collaboration in this investigation has been incredible and the method can be used in any subject. The great game of NBF will be explained further down.

From NCTM:

Before the students knew it was related to assessment we just played it and discussed it. Kids love it. Some of my students decided that the dice would decide if they remained standing or sat down. If that made no sense, go back and read the rules, it won’t take long. Some used odd versus even, low or high.

From NCTM - Fabulous site for mathematics teachers

We used the SKUNK dice simulator from NCTM, real dice which I rolled. then a student wanted ‘control’ so I happily passed it over to who has now become “Mr. Snake Eyes”.

Their task is to make a SKUNK user guide. How to be a successful skunk player both as a high roller and a play safe type gambler. They need to produce strategies for both types of players and back up them up with evidence. The assignment will be submitted on Tuesday.

When I teach probability I introduce the great game NBF. NBF stands for New Best Friend. Every lesson students get an NBF. I have the tables numbered from one to twenty-four. As the kids come into class they reach into the NBF lucky dip and pull out a number. This is where they sit. For the first couple of minutes they must chat with their NBF. I told my kids that being able to talk to anyone is such a great skill to have. While they might be out of their comfort zone, it’s worth it. They now look forward to it. Two kids actually sat next to each other three classes in a row. “What’s the chance of that?”, when you get a genuine question like that, you stop, grab the student directed moment and run with it.  

What I hadn’t anticipated was how wonderful the great game of NBF was going to be for an investigation. Students worked together in the first lesson to collect data, make predictions, record results. Their homework was just to review what they had recorded so that when they met their NBF the next lesson they could explain it to them. NBFs share ideas and results and the investigation took shape in a way that wouldn’t have happened if they had continued to work with their same friend each lesson.

I told them that long ago mathematicians would travel for weeks, even months to meet someone working in the same field, to find an NBF in the mathematical world, that they were fortunate to pick so many wonderful mathematical minds and to share ideas.  This is how each lesson began.

3d people partner.

3d people partner by 姒儿喵喵 licensed under CC by A SA

Were they taught tree diagrams and outcome tables? No. Did they appear? Yes, everywhere. All year we have focussed on the MYP criterion of Communication and you could see this paying off for this investigation. When this investigation finishes we will spend a lesson on a few more games, then they can just start their design of the casino game with their teacher in the background nudging them forward, showing them the mathematics they need when it is needed, in context.

If you have an investigation over a week or more and students can work together but need to produce individual reports, I can’t recommend this enough. Totally by chance this came my way, and that’s quite fitting. Oh yes, and it is fun. And learning should be fun.


An interesting thing to do if you are teaching probability, is for you to grab a random number for NBF and give to the students and then discuss how they felt and if it actually made any difference.

An extra resource I found is from www.100people.org that I used for a statistics unit for grade six. On page 24 of this document is the language of observation and analysis. Great for any subject that studies results. Remember we are all EAL teachers. It’s important to support our students in their writing.


One thought on “NBFs: “What’s The Chance Of That?”

  1. Pingback: Casino Night and Gamification « #AoD happily wearing my inner geek on the outside

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