Partitioning Teen Numbers

Introduction

Welcome to today’s lesson plan on partitioning teen numbers! We'll build on your learner's understanding of numbers 11 to 19. These are often referred to as "ten and a bit" numbers. By the end of this lesson, your learner will be able to confidently work with these numbers, understanding their structure and composition, and applying this knowledge to various math problems.

Before beginning the lesson, your learner should be able to identify and write numbers 11 to 19. They should also be comfortable partitioning numbers in different ways.

Key Concepts for Partitioning Teen Numbers

Here are a few concepts that are helpful to know for the lesson:

• Tens and Ones Structure: Numbers 11 to 19 can be broken down into a combination of tens and ones. For example, the number 13 is composed of one ten and three ones. This method of partitioning helps learners understand the structure and composition of teen numbers, making calculations more intuitive.
• Partitioning with Tens Frames: Tens frames are visual tools that help learners see the composition of numbers. A tens frame consists of a grid of ten squares. To represent 14 using tens frames, fill one frame completely (representing ten) and place four additional objects in a second frame. This visual representation reinforces the idea of one ten and four ones.
• Partitioning with Part-Part-Whole Diagrams: Part-part-whole diagrams, such as cherry or bar models, show how numbers can be split into parts. To represent 14 in a part-part-whole diagram, draw a large circle (or bar) labeled 14 and two smaller circles (or sections of the bar) connected to it, labeled 10 and 4.
• Partitioning with Equations: Equations provide a symbolic way to represent the partitioning of numbers. For example, 14 can be written as: 14 = 10 + 4 or 14 = 4 + 10. These equations help learners understand the relationship between the parts and the whole.

Teaching Plan

The following activities will help your learner become confident with partitioning numbers 11 to 19. Remember to go at a pace that is comfortable for your learner.

Examples and visuals to support the lesson:

1. Composition of Teen Numbers

• Begin by explaining that teen numbers (11 to 19) are composed of ten and additional ones. Use tens frames to demonstrate this concept by filling one frame completely before moving to the next.
• Show how to record the partitioning into tens and ones using part-part-whole diagrams and equations. For example, 17 can be shown as 10 + 7 and also as 7 + 10.
• Provide your learner with 11 to 19 objects and two tens frames. Have them practice placing the objects into the frames and recording the numbers in part-part-whole diagrams and equations.

Skill Check
I can use ten-frames and diagrams to split teen numbers into ten and some ones.

2. Structured Representations

• Demonstrate the structure of teen numbers using counters and tens frames, ensuring your learner sees that ten ones are equivalent to one ten.
• Show the equations in various forms, such as 11 = 10 + 1 and 11 = 1 + 10. Practice saying the numbers and writing equations to build fluency.
• Have your learner use the following stem sentence to describe teen numbers: "__ is equal to 10 plus __."

Skill Check
I can write addition equations to show teen numbers split into ten and some ones.

3. Identifying Quantities with Pictures

• Vary the images used to represent the quantities, ensuring your learner can quickly identify the number shown without counting. Include some images that are arranged with the "ten" on the left and some with it on the right.
• Make sure that your learner can say the number shown, match the image to a number card, and write the number themselves.
• Encourage your learner to describe how they know what number it is using full sentences. For example: "I know there are twelve because twelve is equal to ten plus two.”

Skill Check
I can recognize the number of objects when they are split into ten and some ones.

4. Solving Addition and Subtraction Problems

• Next, use part-part-whole diagrams and real-world problems to practice addition with teen numbers.
• Gradually introduce missing sum equations. Include some equations with the tens part missing and some with the ones part missing.
• Progress to subtraction problems using part-part-whole diagrams with a missing part and real-world contexts.

Here are a few examples of real-world contexts:

• Sam has ten marbles in his collection. Then his friend gives him five more. How many marbles does Sam have now?
• Jaz has a two-cent coin and a ten-cent coin. How much does she have altogether?
• There are fifteen pens altogether. Ten are shown and some are hidden. How many pens are hidden?

Skill Check
I can solve addition and subtraction problems that have teen numbers split into tens and ones.

5. Challenge Activities

• For an additional challenge, introduce problems that involve partitioning tens or ones in different ways. Keep the focus on combining ten with ones to make teen numbers.
• For example, 15 = 2 + 10 + __. In this equation, your learner may realize that 15 is ten and five ones. Since there are already 2 ones, there are 3 ones missing. Therefore, 3 is the missing number.
• You can also provide subtraction problems with two subtrahends. For example, 17 - 5 - 5 = __. Encourage your learner to find the missing numbers by focusing on the "ten and a bit" structure.
• Build on your learner's understanding of comparing numbers to have them solve inequality problems with teen numbers. Remind them that we use the symbols >, <, and = to compare numbers.

Summary

Through this lesson plan, your learner will gain a strong understanding of partitioning teen numbers and the concept of ‘ten and a bit’. By practicing with various visual aids, part-part-whole diagrams, and real-world problems, they will become proficient in recognizing and working with numbers 11 to 19. This foundational skill is crucial for their future success in math.

Teaching Plan adapted from NCETM under OGL license v3.