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5th Grade Math – Decimal Place Value

Clip 8/29: Day 1: Decimal Lesson Part C


Erika Isomura’s students continue pair work on the problems, defending their thinking to each other. They make use of the sentence stems Erika gave them (e.g., “I think ____ because,” “This way is easier on our brains because______,” “What do you think?” “How did you feel about this problem?” “I knew it was this answer because I thought about the 0s”).

Erika engages pairs in explaining their thinking (e.g., “Show me in your answer,” “Do you think that will work every time?”). She reminds her students to note moments in their work that suggest that they might need to have a discussion about it.

Teacher Commentary

My students are starting to think that a pattern is happening. You really see linking it to the fractions and then the notation and then the patterns. It's no joke. This was the first time they really thought about how do decimals get written and how does that relate to the names. I wasn't sure when they would bring up the language. But they got really agitated about naming it and how it's written and how the names relate, because this looks different from that.

They couldn't see a connection between them, so I just told them: "Here's one way people sometimes think about the connection. So in the 10ths, some people think that that one zero is the ones place here. That's one way." Just a little mnemonical cheat sheet to remember how many places you go over. That afternoon was our first formal naming [of] the places, or decimals.

I was really impressed, because quite a few of them said, "If you think about the denominator, the tenths have a 10. If the ones had a denominator of one, it would just be that number, which is a whole. Therefore, it would never be on the parts side." I thought, "Cool! I think they've got some pretty good understanding about some fractions with this value.”

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