September 19: Using a Ruler

Students were given a quiz with two questions: read from an English ruler and from a metric ruler. Before the quiz most students claimed to know how to use a ruler, but many spent quite a while on the quiz and only three students got both questions correct. There was a roughly even split between those who missed both questions and those who missed only the English ruler. Nobody read the English ruler correctly and missed the metric ruler. 

The quiz was quickly graded (1pt for English ruler, 2pt for metric ruler). Metric was weighted more because students were expected to know that system better than English. The uneven weighting also makes it very easy to scan the grades and know exactly which questions the students missed based on grade (ie, anyone who scored 2pt read the English ruler incorrectly).

For the most part I thought the explanations of the systems were clear. Good explanation of how the two systems differ, how to read English and why it is that way, how to read metric. Covered some better methods to read off rulers faster, which I think will be useful once the students gain mastery. One method was to subtract from the nearest whole (ie, 15/16 = 1 - 1/16). The other was to use mixed groupings. 15/16 = 1/4 + 1/16 = 4/16 + 1/16. It might be worth mentioning (perhaps later, after students have some familiarity) what to do when the thing being measured doesn’t fall neatly on a tick mark. Depending on the task (and precision needed) I either split the difference (ie, something between 15/16 and ⅜ would be ~11/32), round (just call it ⅜), or make a note to indicate its a little larger (15/16+). Probably only the first solution would be appropriate to talk about since it’s the most formal.

One thing that struck me was that the pacing seemed very slow, and yet there were students who still seemed to struggle. It’s difficult to put yourself in the mindset of somebody with little experience on the topic. Perhaps the pacing is slow after all, but this also highlights the difficulty of teaching something that one is extremely familiar with. It seems so fundamental and obvious that it becomes a struggle to slow down and let others absorb the concepts.