Bar Models in Addition and Subtraction Within 1000

Table of Activities

​What are we doing today?

1. Lesson Objectives

2. Identify part-part whole

3. Polya 4-step in Solving Word Problems

4. Math Symbols

5. Bar Models

6. Quizziz

Lesson Objectives

1. Identifying parts and whole

2. Defining parts and wholes

3. Writing parts and wholes

4. Solving parts and wholes in word problems using addition and subtraction

5. Identifying keywords like "fewer" and "more" in the word problems

6. Introducing the 2 types of bar models in the Additon and Subtraction Word Problems

​How to identify part-part whole?

​Number bonds

​Part-part whole bar model

​Activity Instructions

Girls from 2L are to stand up.

Count and write down the

number of girls who are standing up.

​

Fill in the Blanks

Girls from 2L class are to stand up.

Count and write down the number of girls who are standing up.

​Activity Instructions

Count and write down the

number of boys who are sitting down.

​

Fill in the Blanks

Count and write down the number of boys who are sitting down.

Draw

The total number of boys and girls in 2L will make up the whole. The number of girls in 2L will make up 1 part. The number of boys in 2L will make up the other part. Fill in the numbers correctly in the number bond below.

Draw

We have discovered that a whole can be a whole class that is made up of parts. Fill in the part-part whole model using the numbers in the number bond.

Word Problem Sums

Polya's 4-Step Word Problem Solving

Word Problem Sums

​ 1. Understand: underline keywords and numbers

2. Plan: draw a bar model

3. Do: Add (+) or Subtract (-)

   Mutiply (x) or Divide (÷)

4. Look Back: Check your answers - work backwards

Multiple Choice

What is the first (1st) step in Polya's Word Problem Solving Method?

• Plan

• Do

• Look back

• Understand

Multiple Choice

What is the second (2nd) step in Polya's Word Problem Method?

• Plan

• Do

• Look back

• Understand

Multiple Choice

What is the third (3rd) step in Polya's Word Problem Method?

• Plan

• Do

• Look back

• Understand

Multiple Choice

What is the fourth (4th) step in Polya's Word Problem Method?

• Plan

• Do

• Look back

• Understand

Math Symbols

We use symbols when writing number sentences.

+ - =

​These symbols help us understand how the whole numbers and the parts of the word problem work together.

​

• Sum

• means add together

​Plus +

• Difference

• means to take away or subtract

​​Minus -

• ​the value

​​Equal =

​Part - part whole

Bar Models

Part-part Whole Model

• use when comparing 2 different quantities with one that is unknown or

Part-part Whole Model

• use when 2 different quantities are known and to find the total or sum of the 2 values

Comparison Bar Model

​use to compare 2 different quantities in which 1 is greater than the other

Multiple Choice

Kayla made a bracelet with 56 beads. She lost 23 beads.

How many beads does Kayla have on her bracelet?

What bar model is shown?

• comparison model

• addition part-whole model

• subtraction part-whole model

Draw

Kayla made a bracelet with 56 beads. She lost 23 beads.

How many beads does Kayla have on her bracelet? Solve this question.

Multiple Choice

Matthew has 156 toy cars. Jerome has 269 toy cars. How many toy cars do the boys have altogether?

What bar model is shown?

• addition part-whole bar model

• subtraction part-whole bar model

• comparison bar model

Draw

Matthew has 156 toy cars. Jerome has 269 toy cars. How many toy cars do the boys have altogether? Solve this question.

Multiple Choice

What bar model is shown?

• addition part- whole bar model

• comparison model

• subtraction part-whole bar model

Multiple Choice

How do we solve this to find the number of boys?

• 134 + 15

• 134 - 15

Draw

There are 134 girls at a concert. There are 15 fewer boys than girls at the concert. How many boys are there?

Poll

Drawing bar models when solving word problems help me understand the questions better.

• Yes, I agree

• No, I don't agree

• I'm not sure