standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
problem_activity: Narrative
The purpose of this activity is for students to make connections between written numbers and expressions. In the activity synthesis, students see each teen number written as an equation. In this unit, when reading equations to students, read the equal sign as “is.” For example, read
\(10 + 3 = 13\)
as “10 plus 3 is 13.” The equal sign will be read as “equals” in the next unit.
MLR8 Discussion Supports.
Synthesis: At the appropriate time, give students 2–3 minutes to make sure that everyone in their group can explain how they organized the numbers and expressions. Invite groups to rehearse what they will say when they share with the whole class.
Advances: Speaking, Conversing, Representing
Engagement: Develop Effort and Persistence.
Some students would benefit from having clear examples of the expectation of group work in this activity. Invite students to generate a list of shared expectations for group work. Ask students to share explicit examples of what those expectations would look like in this activity.
Supports accessibility for: Social-Emotional Functioning
Required Materials
Materials to Copy
Numbers and Expressions Cards
Required Preparation
Create a set of cards from the blackline master for each group of 4.
Launch
Groups of 4
Give each group of students a set of cards.
“Work with your group to organize the cards in a way that makes sense to you.”
Activity
6 minutes: small-group work time
Monitor for students who organize the numbers and expressions as shown in the sample response.
Student Response
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Activity Synthesis
Invite a group of students to share how they organized the numbers and expressions or display the image in student responses.
“What do you notice about the numbers and expressions when they are arranged this way?” (They’re in the order that we count. The first number stays the same. The second number is 1 more each time. All the expressions have a 10. The second number starts at 1 and is one more each time. The expressions match the numbers.)
“Which number does
\(10 + 1\)
represent? How do you know?” (11)
“
\(10 + 1\)
is 11. We can write that as
\(10 + 1 = 11\)
.”
Demonstrate writing equations for each number and expression.


aligns: no