I have always found the 'Tug of War' thinking routine intriguing, but I didn't want to force it's use as I felt like it wouldn't be meaningful if I just plugged it in anywhere. I tried it earlier this year, but it flopped... big time! I put the idea of using it on the back burner and figured that one day I'd discover a good use for it. Last month during our measurement unit, I had this idea that using it to assess their understanding of the Metric System and the U.S. Customary Systems of measurement would be really fun and it might actually work. I posed the question "Which system of measurement do you find easier to use?" On one side I had the metric system, and the other the U.S. Customary. (I then used a broken tape measure to make it look cute!). This time, to my surprise, it went much better than the first attempt. The kids were really thinking about which they preferred, and it was very close as to which was preferred.
The majority of the students that chose the metric side commented on the conversions and how it was easier to add or subtract zeros to find other measurements within the system.
The students that chose the U.S. Customary system made connections between how often they have practiced or used the system and that 'practicing it more makes it easier'.
I found it amazing that they were able to self reflect and think about the two sides and really make evaluative decisions about their learning and capabilities and mathematicians.