# Adding by 1

## Overview

You can find how many there are in all by adding two groups of objects together.

In this lesson, we will learn how to **add by 1** to any group of objects.

There are many examples in real-life where you will need to use the skill **adding by 1**. Pretend you are having a birthday party and there are 10 people in total including you celebrating.

**Suddenly**, one of your friends shows up to your front door unannounced to join your birthday party. Now, we have **one more** meaning we need to **add by 1 **to find the total number of people at your party.

Now, let’s take a look at some more examples using pictures.

**Let’s take a look at the example above.**

There are **2** circles in the first group and there is **1** more circle in the second group.

We can ADD them. We do this by joining the **2** amounts together.

This will give us the total number of circles IN ALL.

When we ADD **2 plus 1**, we have **3** in all.

We say: **TWO plus ONE equals THREE**.

We write it like this: **2 + 1 = 3**

In this problem, we are joining together two groups of dogs.

We are ADDING them together.

This will give us the total number of dogs.

When we ADD **4 plus 1**, we have **5** in all.

We say: ONE plus TWO equals THREE.

We write it like this: **4 + 1 = 5**

This time, we are working with the numbers **8** and **1**.

These numbers are known as ADDENDS.

**Addends** **are the amounts that will be joined together.**

This problem reads as **8 + 1 = 9**.

When the ADDEND **8** is joined with the ADDEND **1**, we get a SUM of **9**.

The SUM is used to describe the total amount.

When we add ONE MORE to a group of objects, we can remember that the SUM will be the number that comes next when we are counting.

5 + 1 =

For example, **5 + 1 = 6**. We also know that when we count, the number that comes after **5** is the number **6**. This can help us to add quickly and correctly when adding **1** to a group.

12 + 1 =

Let’s try another example. What is **12 + 1?** We can add or count on from the number **12**. We know that the number that comes after **12** is the number **13**.

Therefore, **12 + 1 = 13.**

1 + 9 =

Here is another example. This time our 1 comes first and our group comes second. We can still solve in the same way. What is **1 + 9?** We can add or count on from the number **9**. We know that the number that comes after **9** is the number **10**.

Therefore, **1 + 9 = 10.**

Look at the example above. Two groups are being joined together to find the total.

**5** bees plus **1** bee will tell us how many bees there are in all.

When we count, we know that the number that comes after **5** is **6**.

Therefore,** 5 + 1 = 6 bees**.

There are **6 bees** in all.

There are many different words that are used to describe addition. Take a look at the picture below to review the keywords that describe the mathematical operation – **addition**.

Knowing these keywords will help you understand that in order to solve the problem, you must add. All the examples above dealt with pictures.

**Let’s try adding by 1 in word problems. **

In the problem, the pencils are being joined together. The key words are **AND** as well as **ALTOGETHER**. This helps tell us that we need to ADD.

**ONE** blue pencil is joined with **THREE** red pencils and this will give us the correct SUM.

We can count on one from three to help us find the answer.

**1 + 3 = 4 pencils**

There are many additional strategies you can use to help you add correctly. We will learn about these in other lessons.

### Practice Question 1

** Write the addition sentence and solve the problem below.**

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### Practice Question 2

**Write the addition sentence and solve the problem below.**

### Practice Question 3

**Take a look at the math sentence below. Draw a picture to match it. Then solve.**

1 + 8 =

### Practice Question 4

**Look at the groups below.**

**How many are there in all?**

**Write an addition sentence and solve.**

### Practice Question 5

**Let’s try one more problem!**

**Look at the groups below.**

**How many are there in all?**

**Write an addition sentence and solve.**

Hooray! You’re ready to take a quick quiz on adding by 1!

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