options: Functions: students learn to define, use, and evaluate functions to model relationships between quantities.

Counting & Cardinality: students learn to know number names and the count sequence, count to tell the number of objects, and compare numbers.

Number Systems and Quantity: students learn to understand the complex number system and reason quantitatively.

Ratios & Proportional Relationships: students learn to recognize, describe, represent, and reason with ratios, rates, proportional relationships, and percent.

Geometry: students learn to classify geometric figures by their properties, and understand and compare the relationships between them. Students develop and use formulas to compute lengths, areas, and volumes, and they use transformations to generate new shapes and compare existing ones. Geometry can be studied with and without coordinates.

Statistics & Probability: students learn to analyze and produce data distributions, and build understanding of univariate and bivariate data. They learn to interpret data, make statistical inferences, justify conclusions, understand rules of probability, and use probability to make decisions.

Measurement & Data: students learn to work with data and measure attributes such as time, money, length, area, and volume. They may learn to compare measurements to operations and convert between different units of measure.

Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.

Operations & Algebra: students learn to solve problems using algebraic thinking and operations such as addition, subtraction, multiplication, and division. They may learn to identify and explain arithmetic patterns, evaluate or manipulate numerical expressions, and reason with equations and inequalities.

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.

Modeling: students learn to choose and use appropriate mathematics and statistics to analyze real-world empirical situations, improve decisions, and report on their conclusions and the reasoning behind them.
problem_activity: Narrative
The purpose of this activity is for students to use their understanding of place value to find the number that makes each equation true. Students must consider how units may be composed or decomposed to find the unknown number (MP7). The number choices intentionally emphasize the types of compositions and decompositions students may use to add and subtract within 1,000. The synthesis focuses on the equations that involve composing or decomposing two units.
Required Materials
Materials to Gather
Base-ten blocks
Launch
Groups of 2
Give students access to base-ten blocks.
Activity
5 minutes: independent work time
“Take turns sharing your thinking with your partner. Show or explain how you know your equation is true.”
3 minutes: partner discussion
For finding the number that makes 2 hundreds + 9 tens + 17 ones true, monitor for students who:
explain by using base-ten blocks or place value diagrams
explain how they noticed when they would need to compose or decompose more than one unit
Student Facing
Find the number that makes each equation true.
5 hundreds + _____ tens + 6 ones = 5 hundreds + 5 tens + 16 ones
1 hundred + 1 ten + 17 ones = 1 hundred + _____ tens + 7 ones
4 hundreds + 15 tens + 3 ones = _____ hundreds + 5 tens + 3 ones
4 hundreds + 3 tens + 7 ones = 3 hundreds + _____ tens + 7 ones
7 hundreds + 8 tens + 4 ones = 7 hundreds + 7 tens + _____ ones
[IMG]
6 hundreds + 9 ones = 5 hundreds + _____ tens + 9 ones
2 hundreds + 9 tens + 17 ones = _____ hundreds + 7 ones
3 hundreds + 1 ten + 5 ones = 2 hundreds + 10 tens + _____ ones
If You Have Time: Make your own equation with a missing value for your partner.
Student Response
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Advancing Student Thinking
If students create equations that are not true, prompt students to make the known side of the equation with base-ten blocks, consider asking:
“How can you compose or decompose units to show the equation is true?”
Activity Synthesis
Invite previously identified students to share their method for finding the unknown number for 2 hundreds + 9 tens + 17 ones = _____ hundreds + 7 ones.
For students who use base-ten blocks, draw place value diagrams to record their explanation.
Consider asking:
“How do you know both sides of the equation are equal?”
“Did you compose or decompose units? Did you compose or decompose more than one time?”


correct_option_index: 9