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

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

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

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.

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

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.

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.

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.

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

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.
problem_activity: Narrative
The purpose of this activity is for students to subtract a two-digit number from a two-digit number in a way that makes sense to them. Students build on their understanding of decomposing a ten when subtracting a one-digit number from a two-digit number to subtract two-digit numbers. The synthesis is devoted to presenting and comparing techniques students use to find the difference, including diagrams and equations (MP3).
This activity uses
MLR8 Discussion Supports
. Advances: listening, speaking, conversing
Representation: Develop Language and Symbols.
Synthesis: Make connections between representations visible. Ask students to verbalize the connection between the expression and the blocks.
Supports accessibility for: Visual-Spatial Processing, Language, Memory
Required Materials
Materials to Gather
Base-ten blocks
Connecting cubes
Launch
Groups of 2
Give students access to connecting cubes and base-ten blocks.
Activity
“Find the value of each difference and share your method and solution with your partner.”
7 minutes: independent work time
MLR8 Discussion Supports
“After your partner shares their method, repeat back what they told you.”
Display the sentence frames:
“I heard you say . . . .”
“Our methods are alike because . . . .”
“Our methods are different because . . . .”
5 minutes: partner discussion
Monitor for students who use base-ten blocks to show decomposing a ten.
Student Facing
Find the value of each difference. Show your thinking. Use blocks if it helps.
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[IMG]
Student Response
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Advancing Student Thinking
Some students may not use base-ten blocks to find the difference. Prompt them to show their thinking in a way that could help others understand. Ask them to write expressions to show the steps they took when appropriate. Consider asking:
“How did you find the value of the difference?”
“What could you add to your diagram to help your partner understand what you did?”
“How could you use equations to show the steps you used?”
Activity Synthesis
Invite previously identified students to share.
“What did _____ do to solve the problem? How can we record it?”
30 seconds: quiet think time
Share responses.
Show how to represent solving with base-ten blocks with drawings and equations.
“How are these representations like the way _____ used base-ten blocks to find the value of the difference? How are they different?”


correct_option_index: 10