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Lesson

1st Grade Math - Developing Student Understanding of Non-Standard and Standard Measurement

Clip 11/17: Measurement Lesson Part D3

Overview

After the first-grade students have recorded their measurement findings on posters, Tracy Sola reconvenes the group, praising their work: “You were very, very careful measuring scientists, weren't you?”

Tracy discusses the “6 cubes” poster and notes that several groups put the can on that poster, but that with a (rectangular) box of tea, some students put it on the “7 cubes” poster, and others on the “4 cubes” one. She asks them why that might be.

Students turn-and-talk to a partner, and several share that some groups might have measured different sides of the box: “Some people measured on the long side; some people measured on the short side.” Tracy also engages the group in discussing how partners measured an object that did not exactly measure 8 or 9 cubes, but ended in the middle of a cube’s length.  

Teacher Commentary

I was wondering what would happen when they got an object in which you could measure different dimensions of that object; and that turned out to be an interesting thing that was a little bit dissonant for them. 

It turns out that the tea box was four cubes in one dimension and seven cubes in another dimension. And when the one group went over and put it on the "four" poster and the other group then started to list it on the "seven" poster, the boys who had measured it as four were trying to tell the girls who measured it as seven that it wasn't seven and that it needed to go on the four poster. And so that was a really interesting time to see them making sense of how an object could have more than one dimension and how it was okay for it, really, to be both: that, depending on which side you measured, the box could be four or seven cubes long.