Tuesday 29 September 2015

MPM2D - Day 15: Oreos & SolveMe Mobiles

Today was Oreo day. 

I told my students all about Mr. Kraft and Mrs. Runkle, whose story can be found on Nathan's blog here. They were just as grossed out as me that Nathan would eat cookies that Mrs. Runkle had licked. Once the story was set up, I asked the question: who was eating more calories? (this is all stolen from Nathan's blog)

I gave each group a large whiteboard to work on and the conversations naturally flowed. Along the way I gave each group cookies to keep them inspired. 

Only there were more cookies than people and some were regular Oreos and others were double-stuf Oreos - distributing them fairly among the group members became a whole different problem to solve!

Before circulating to see how they were doing, I checked yesterday's homework (set 12). I was delighted to see that they really seem to understand how to solve (this particular type of) word problems using elimination. They rocked that homework!

Here are their solutions to the Oreo question:

Lots of great, very similar solutions (we did talk about the one with the correct work, but incorrect conclusion). This next one started with a slightly different strategy, which was the catalyst for some good discussion.

I then showed my students Nathan's blog post and they saw the various ways the question had been answered. I am trying to encourage my students to look for different ways of approaching a problem and this did a great job of demonstrating just that.

As some groups had worked through the Oreo question faster than others, I returned the homework that had been handed in yesterday (set 11) for them to look over and correct. Trying to ensure that they take the time to learn from their mistakes means that I will devote some class time to this practice. 

Next we solved some puzzles. I introduced them to SolveMe Mobiles, which, sadly, do not work on mobile phones (but I still love them). We did a couple of simple ones together to make sure everyone understood how they worked and then tackled #63, then #64, shown here:

Followed by #67 (below) and #71.

I find it really interesting that students who can solve these "in their head" tell me that they can't solve them algebraically. However, if they tell me step by step what they did to solve it, and I write down each step, they see that it all matches. Working on that perseverance...

Today's homework is a mixture of questions which can be found here.


  1. Mary - I am blown away every day by the intentionality in your planning and your regular and detailed blogging. Your students are hugely lucky to have you as a teacher, and I am lucky to be [one of the many] recipients of your generosity in sharing. Truly - you inspire me. - WM

    1. Thank you for reading and for taking the time to write that. I feel fortunate to be part of such a great math community.