Elementary Pull-Out: Crazy 10's

The Elementary Mathematician, COMAP's award-winning K-6 newsletter is available for the first time in electronic format. Each issue contains a collection of K-6 mathematic lessons that are fun to teach and exciting to learn.

Each issue of The Elementary Mathematician contains a Pull-Out section which includes thematic lessons based on the national census, wildlife, other cultures, technology, and provides a practical way to bring the concepts and pedagogy of the NCTM Standards into your classroom. 

Note: The information below was created with the assistance of AI.

Level of Mathematics
Target Grade Levels: Kindergarten through 2nd Grade (K–2)

This is explicitly stated in the document and supported by:

The use of calculators and 100s charts.

The mathematical focus on adding and subtracting 10.

Instructional strategies centered around guided practice and pattern recognition appropriate for early elementary students.

Application Areas
This lesson applies mathematics in developmentally appropriate and conceptually rich contexts:

1. Numeracy Development
Strengthening understanding of the base-ten number system.

Promoting fluency in operations with whole numbers.

2. Pattern Recognition
Observing and analyzing predictable patterns on a 100s chart.

Using visual aids to reinforce arithmetic structure.

3. Tool-Based Exploration
Integrating calculator use to reduce cognitive load for computation and enhance pattern discovery.

4. Visual-Spatial Reasoning
Coloring and mapping number patterns encourages spatial understanding of numerical relationships.

Prerequisites
Students should have the following foundational skills:

Ability to read and understand two-digit numbers.

Familiarity with basic addition and subtraction.

Basic calculator usage (entering numbers and performing operations).

Experience using a 100s chart to locate numbers.

No prior knowledge of place value terminology is necessary, but conceptual exposure is reinforced through pattern analysis.

Subject Matter
The lesson centers around these mathematical concepts:

1. Addition and Subtraction by 10
Operational fluency with increments/decrements of 10.

Emphasis on the vertical movement on a 100s chart to visualize how numbers increase/decrease by ten.

2. Place Value Awareness
Encourages noticing that adding/subtracting 10 affects only the tens digit, not the ones digit.

3. Pattern Discovery
Students build awareness of consistent numerical shifts and are guided to explain what they see.

4. Mathematical Communication
Teachers prompt students to reflect verbally on what happens when they perform operations.

Correlation to Mathematics Standards
This lesson aligns with several Common Core State Standards (CCSS) for grades K–2:

CCSS.MATH.CONTENT.K.NBT.A.1
Compose and decompose numbers from 11 to 19 into ten ones and some further ones.

CCSS.MATH.CONTENT.1.NBT.C.5
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

CCSS.MATH.CONTENT.1.OA.C.6
Add and subtract within 20, demonstrating fluency.

CCSS.MATH.CONTENT.2.NBT.B.8
Mentally add 10 or 100 to a given number 100–900, and subtract 10 or 100 from a given number 100–900.

Mathematical Practices

MP2: Reason abstractly and quantitatively.

MP7: Look for and make use of structure.

MP5: Use appropriate tools strategically (calculators, charts).