Thursday 15 November 2018

Similar Triangles Introduction

Somehow this is the week when I am getting caught up on blog posts. Why this week? Apparently extra chaos in my life helps me need to cross things off my to-do list. Two kids with potential concussions and one feeling like throwing up seems to be the motivation I need to blog. Go figure.

Ages ago, in my grade 10 applied class, I made a new intro to similar triangles. I liked it mostly because it was simple and allowed my students to practice other skills they had recently learned, namely right-angle trig and sum of squares (Pythagorean theorem). It looked something like this - what "What do you notice?" at the bottom.

This is what we did with it:

Nothing fancy, but it worked so I thought I would share. I think this qualifies as #unsexymath.

If you would like the file, you can find it here.

Marshmallow Challenge

I have not blogged for a while and this post is about six eleven weeks overdue. On the first day of school I do the marshmallow challenge with my grade 12 classes. I do not know who deserves credit for this activity (if someone knows, please pass that along) but it's a great team-building exercise that requires collaboration to be completed in the time allowed.

I hand out cards to organize students into random groups. They start by introducing themselves to their teammates. I then have the groups brainstorm ideas before the clock starts. And then the fun begins. I love watching them try strategies and listening to their conversations. Inevitably they frantically try to finish before the time runs out only to see their structure tilt over when they place the (surprisingly heavy) marshmallow on top. I measure the towers to determine a winning group, but it's really not about winning. 

What I did differently this year, which is really what I wanted to share, was to ask debrief questions after the activity that mirror the great things I see during the activity. I wanted them to think about how collaborating can help a group reach a goal. How it is important to listen and to talk and that it is important that everyone in the group is engaged. You can find the questions I asked here - I looked at ones that others have asked to get ideas so thanks to all those who have shared in the past. I want to focus on a small, but important part. I start by having them fill in this table:

Firstly, they needed to know the names of their teammates. Secondly, they needed to say something complimentary about each of their teammates who are often people that they have never really interacted with before. And they did. They did such a good job. They all found things that their teammates did well. This was important to me because I believe all my students bring positive things to my class. And that along with learning math, we will learn how to be good, kind citizens.