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Lesson

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

Clip 12/17: Measurement Lesson Part D4

Overview

Tracy Sola continues to engage her first-grade students in a conversation about measurement, expanding on the idea of what approach they should use if the size of the object in cubes falls “in between.”

Several students share their ideas, and Sola summarizes: “Okay, so when we're measuring, we need to think about what to do when something isn't exact and whether we have a good reason for adding another cube or not. And that's really your call. I think we can argue either way, right? And you just need to make a decision and then defend it.”

Teacher Commentary

We needed to make sense of things that were not an exact amount of cubes high. I think the blue cup was eleven and-a-little-bit-more high, and so some people had it on the "eleven" poster and some people had it on the "twelve" poster. 

And so, it was interesting for students to think about what was the right thing to do with that. And so some said, “Well, it didn't quite make it, so I needed to add another cube.” And another student said something like, “Well, it's almost there. If we add another cube, it's going to be too much.” I purposely left that as unresolved because it was making sense of a part, a remainder.
 
It’s something that we can start thinking about now in first grade, but that concept isn't really a standard until much later. I just left that as something to think about, saying, “You know, I don't care which way you go on this, but you just need to justify it. You need to give the reason why.”