options: 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.

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.

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.

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

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

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.

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.

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.
problem_activity: Narrative
The purpose of this activity is for students to describe the structure of an array by identifying the number of columns, the number of objects in each column, and the total number of objects. They learn that the columns of an array go up and down. Students begin to reason about how they can use the structure of the array to find the total number of objects without counting by 1.
This activity uses
MLR8 Discussion Supports. Advances: speaking, conversing
Representation: Develop Language and Symbols. S
upport understanding of the rows and columns by inviting students to act it out. For example, use students to create the first array (3 rows of 2). Discuss the students who create the rows. Now switch to talking about columns (2 columns of 3). Discuss the difference in which students create the columns.
Supports accessibility for: Visual-Spatial Processing, Organization
Required Materials
Materials to Gather
Counters
Launch
Groups of 2
Give students counters.
“Use your counters to make an array with 3 rows with 4 in each row. Make sure the counters in each row line up with the counters in the other rows.”
Display counters in an array as shown:
[IMG]
“Arrays are made up of rows, but they also have columns that go up and down. How many columns are in this array?” (4)
30 seconds: quiet think time
Share responses.
“How many counters are in each column of the array you made?” (3)
30 seconds: quiet think time
Share responses.
Activity
“Now you will look at a few arrays to decide how many columns they have, how many in each column, and find the total number of counters. Then you will make arrays using counters and answer a few questions.”
MLR8 Discussion Supports
Display sentence frames to support students when they describe the structure of the array:
“There are _____ columns in the array.”
“There are _____ counters in each column.”
“There are _____ counters in all.”
8 minutes: partner work time
Student Facing
[IMG]
How many columns are in this array?
How many counters are in each column?
How many counters are there in all?
[IMG]
How many columns are in this array?
How many counters are in each column?
How many counters are there in all?
Use 10 counters to make 2 columns with the same number in each column.
How many counters are in each column?
How many rows are in the array?
How could you count these counters without counting by ones?
Use 15 counters to make 3 columns with the same number in each column.
How many counters are in each column?
How many rows are in the array?
How many counters are in each row?
How could you count these counters without counting by ones?
Student Response
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Activity Synthesis
Display student work for an array with 10 counters.
“Describe _____’s array.” (It has 10 counters, it has 2 columns and 5 counters in each column. It has 5 rows with 2 counters in each row.)
“How can we prove there are 10 counters in this array?” (We can skip count by 2. We can add
\(2 + 2 + 2 + 2 + 2\)
. We can add
\(5 + 5\)
.)


correct_option_index: 5