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

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

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.

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

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

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

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.

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

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.

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.

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 choose an algorithm or other strategy to add within 1,000. Students should attend to the details of numbers in the problems that could indicate whether a particular strategy or algorithm is most useful. The important thing is that students choose an algorithm or strategy that they can use efficiently and accurately for the given problem.
Engagement: Develop Effort and Persistence.
Check in and provide each group with feedback that encourages collaboration and community. For example, check that students are staying on task, using math vocabulary, and sharing how they solved the problem.
Supports accessibility for: Social-Emotional Functioning
Launch
Groups of 2
“We’ve been learning about addition algorithms for the last few lessons. Recall that an algorithm is a set of steps that works every time as long as the steps are carried out correctly. But, you know lots of ways to add numbers and lots of representations for showing your work like base-ten diagrams, number lines, and writing words or equations. If it’s not a set of steps that would work every time, we call it a strategy.”
“In this activity, you’re going to have an opportunity to find the value of each of these sums using an algorithm or other strategy of your choice.”
Activity
“Find the value of each sum. Later, you’ll have a chance to share your work.”
7-10 minutes: independent work time
Identify students who used the same strategy to add and those who used different strategies.
Choose a few problems for students to discuss. Consider selecting
\(264 +359\)
(the second expression) and
\(399 + 499\)
(the last expression), which lend themselves to be evaluated with an algorithm and another strategy, respectively.
“Find a partner that added the same way you did. Discuss your reasoning.”
1-2 minutes: partner discussion
“Now find a partner who found the sum in a different way from you. Discuss your reasoning.”
2-3 minutes: partner discussion
Repeat the discussion with 1-2 expressions or as many as time permits.
Student Facing
Use a strategy of your choice to find the value of each sum. Show your reasoning. Organize it so it can be followed by others.
\(199 + 348\)
\(264 + 359\)
\(203 + 75\)
\(316 + 198\)
\(399 + 499\)
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Student Response
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Activity Synthesis
Invite 4-5 students to share a strategy or algorithm that someone they talked to used.
“What strategies or algorithms do you want to practice more?”


correct_option_index: 1