standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Narrative
The purpose of this Choral Count is for students to practice counting on by 5 and to notice patterns in the count. These understandings help students develop fluency and will be helpful later in this lesson and future lessons when students show their thinking when finding total values of sets of coins.
Launch
“Count by 5, starting at 15.”
Record in a single row as students count.
Stop counting and recording at 85.
“Count by 5, starting at 40.”
Record in a single row directly below the first count as students count. Put 40 directly below 20, so that the fives and zeros in the ones place of each number are aligned.
Stop counting and recording at 100.
Activity
“What patterns do you see?”
1
–
2 minutes: quiet think time
Record responses.
Student Response
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Activity Synthesis
“Who can restate the pattern in different words?”
“Does anyone want to add an observation as to why that pattern is happening here?”


aligns: no