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

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

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.

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.

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.

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.

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.
problem_activity: Narrative
The purpose of this activity is for students to learn stage 1 of the What’s Behind My Back center. Students find multiple decompositions of a number. Students snap a tower of connecting cubes into 2 parts and record each decomposition with a drawing and an expression. It may be helpful to give each group of students a single color of connecting cubes so the color of the cubes doesn’t distract students from identifying the two parts. In future stages of this center students hide cubes behind their back after snapping a tower. If needed, you can choose not to use the name What’s Behind My Back when playing this stage or let students know they will do that in future stages of this center.
The recording sheet is printed in the student book for this activity. There is a blackline master available for students to use during centers in future activities and lessons.
When students write an expression to match the connecting cubes, they reason abstractly and quantitatively (MP2).
MLR8 Discussion Supports.
Display and read aloud the following sentence frame to support small-group discussion: “You broke your tower into a group of ____ and a group of ____.” invite students to chorally repeat this sentence in unison 1–2 times.
Advances: Speaking, Conversing, Representing
Required Materials
Materials to Gather
Connecting cubes
Crayons
Materials to Copy
What's Behind My Back Stage 1 Recording Sheet
Required Preparation
Each group of 2 needs 8 connecting cubes of the same color.
Launch
Groups of 2
Give each group of students at least 8 connecting cubes and access to 2 different color crayons.
“We are going to learn a center called What’s Behind My Back?”
Display a cube tower with 8 cubes.
“Start with a tower of 8 cubes. One partner breaks the tower into 2 parts.”
Demonstrate breaking the tower into 2 parts.
“The other partner describes what happened to the tower. Tell your partner what happened to my tower.” (You broke your tower into a group of 5 and a group of 3.)
30 seconds: partner discussion
Share responses.
“Both partners record the two parts with a drawing and an expression.”
Demonstrate completing the recording sheet with a drawing and an expression.
“Then put your tower back together, and play again. Take turns snapping the tower of 8 cubes into 2 parts.”
Activity
5 minutes: partner work time
Student Facing
8 cubes
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8 cubes
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Student Response
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Advancing Student Thinking
If students snap the cubes the same way each time, consider asking:
“Are there any other ways that you can snap the tower into 2 parts?”
“What if you snapped only 1 cube off of the tower?”
Activity Synthesis
“What did you notice each time you snapped the tower?” (There were always 8 cubes. The 2 parts that we broke the tower into were different each time.)
“What are the different ways that you and your partner found to break the tower of 8 cubes into 2 parts?”
Display a tower of 2 and a tower of 6.
“What expression can we write to represent the 2 parts of this tower?” (
\(2 + 6\)
)


correct_option_index: 9