1.NBT.2.b: Understanding Numbers 11-19

I can understand that the numbers 11-19 are composed of a ten and some ones.

What Your Child Needs to Know

This standard focuses on helping your child understand that the numbers 11-19 are composed of a ten and some ones. For example, 14 is made up of 1 ten and 4 ones, while 18 is made up of 1 ten and 8 ones. This understanding is crucial for developing place value concepts.

This concept builds on your child's understanding that 10 ones can be bundled as 1 ten (1.NBT.2.a) and prepares them for working with larger two-digit numbers. When children understand the structure of teen numbers, they develop stronger number sense and can more easily add and subtract with these numbers.

Real World Practice

Visual models and hands-on activities

Visual Models

1. Ten-Frame Plus Ones

Use a filled ten-frame plus additional counters to show teen numbers (e.g., a full ten-frame plus 4 more counters represents 14).

2. Base-Ten Blocks

Use one ten-rod and some unit cubes to represent teen numbers (e.g., 1 ten-rod and 7 unit cubes for 17).

3. Teen Number Cards

Create cards that show teen numbers with the digit 1 in a different color to emphasize the ten, and the second digit in another color to represent the ones.

4. Place Value Chart

Use a simple two-column chart labeled "tens" and "ones" to show how teen numbers are composed (e.g., 13 has 1 in the tens column and 3 in the ones column).

Everyday Activities

1. Teen Number Hunt

Look for teen numbers in your home or neighborhood (house numbers, prices, page numbers) and have your child explain them as "1 ten and some ones."

2. Grouping Objects

Gather 11-19 small objects and have your child group them as 1 group of ten and some extras, then count and name the number.

3. Teen Number Concentration

Create matching cards with teen numbers and their representations (e.g., "16" matches with "1 ten and 6 ones") and play a memory matching game.

4. Building Teen Numbers

Call out a teen number and have your child build it using a ten-frame or bundled sticks for the ten and loose objects for the ones.

Quick Checks

Strategies and quick activities

Strategies When Your Child Struggles

1. Start with Concrete Models

Use physical objects like base-ten blocks or bundled sticks to show that teen numbers are made of 1 ten and some ones.

2. Connect to Counting

Practice counting from 1 to 20, emphasizing the transition at 10 by saying "1 ten and 1 more is 11, 1 ten and 2 more is 12," etc.

3. Use Consistent Language

Always refer to teen numbers as "1 ten and ___ ones" to reinforce the place value concept.

4. Visual Supports

Create a place value chart with teen numbers written with the tens digit in one color and the ones digit in another color.

5-Minute Practice Activities

Activity 1: Teen Number Sort

Create cards showing teen numbers in different forms (numeral, words, pictures) and have your child match them.

Activity 2: Quick Build

Call out a teen number and have your child quickly build it using a ten-frame and counters.

Activity 3: Teen Number Riddles

Give clues like "I'm thinking of a number with 1 ten and 6 ones" and have your child identify the number.

Activity 4: Decompose and Compose

Show a teen number and have your child tell you how many tens and ones it has, then reverse by giving the tens and ones.

Check Progress

Track improvement

By the middle of the year, your child should:

  • Recognize that teen numbers are made up of 1 ten and some ones
  • Represent teen numbers using objects or drawings
  • Count teen numbers accurately

By the end of the year, your child should:

  • Fluently decompose teen numbers into 1 ten and some ones
  • Write teen numbers correctly and explain their place value
  • Use understanding of teen numbers to solve simple addition and subtraction problems
  • Connect teen numbers to the larger place value system

Mastery Signs

Your child understands this concept when they can:

  • Automatically identify teen numbers as 1 ten and some ones
  • Explain why teen numbers are written with two digits
  • Represent teen numbers in multiple ways (objects, drawings, numbers)
  • Use place value language correctly when discussing teen numbers
  • Apply understanding of teen numbers when solving problems

Differentiation

Support for all learning levels

Below Grade Level

Practice problems focusing on foundational skills needed for this standard.

📥 Download Practice Worksheet

At Grade Level

Standard practice with grade-level appropriate problems.

📥 Download Grade Level Worksheet

Above Grade Level

Challenging problems that extend understanding beyond grade-level expectations.

📥 Download Challenge Worksheet