Addition and Subtraction Lesson: Understand Basic Math

Lesson Overview

• What Does It Mean to Add?
• What Does It Mean to Subtract?
• Strategies for Adding Numbers
• Strategies for Subtracting Numbers
• Understanding Large Numbers
• Working with Two-Digit and Three-Digit Numbers
• Word Problems and Examples
• Important Clues in Word Problems:

In mathematics, adding and subtracting are the first steps toward solving everyday problems. These operations help us count objects, understand changes in quantity, and prepare for more advanced math. For first-grade students, learning how to add and subtract numbers up to 100 builds a strong foundation for future success.

Adding means bringing numbers together to make a larger number, while subtracting means taking numbers away to find what remains. As you move through this lesson, you will explore ways to understand these ideas using simple examples, helpful tricks, and easy-to-read tables.

What Does It Mean to Add?

Addition is a way to find the total number of items when two or more amounts are put together. It helps us solve problems like "How many apples do I have if I get more apples?" It is a skill that supports everyday counting and is often described with words like "plus," "total," and "altogether."

In an addition sentence like 45 + 55, the numbers being added are called "addends," and the result is the "sum."

Key Terms:

What Does It Mean to Subtract?

Subtraction is used when we take some amount away from a number and want to know what is left. It answers questions like, "How many do I have after giving some away?" and "What is the difference between two amounts?" Subtraction involves terms like "minus," "left," and "difference."

For example, in the equation 99 - 90, 99 is the starting number (minuend), 90 is the number being taken away (subtrahend), and the result is the difference.

Key Terms:

Strategies for Adding Numbers

When adding numbers, there are a few simple strategies that can help make problems easier. These are especially useful when dealing with numbers greater than 10. First graders can use tools like fingers, number lines, or objects to help them visualize the process of adding.

Helpful Strategies:

Counting On: Start with the bigger number and count up.

Making Tens: Group numbers to make ten, which is easier to work with.

Column Addition: Line up digits by place value (ones and tens) and add each column starting from the right.

Using Place Value: Break numbers into tens and ones. Add the tens first, then the ones.

Take This Quiz:

Addition and Subtraction Test: Quiz

Strategies for Subtracting Numbers

Subtracting also becomes easier with a few common techniques. When we subtract, we begin with a number and take away a part of it to find out what is left. First-grade students should be able to use number lines, pictures, or small objects to help solve problems.

Helpful Strategies:

Counting Back: Start with the large number and count backward by ones.

Counting Up: Start with the smaller number and count up to the bigger number to find the difference.

Using Place Value: Break the number into tens and ones to subtract step-by-step.

Column Subtraction: Line up the numbers and subtract digits in each place value. Begin with ones, then tens.

Understanding Large Numbers

Even though the numbers get bigger, the method stays the same. Understanding place value helps us work with larger numbers like 9000 or 1000. In first grade, students begin to understand how numbers are made up of thousands, hundreds, tens, and ones.

For example, subtracting 1000 from 9000 involves subtracting one group of a thousand from nine groups of a thousand. This concept builds place value understanding and prepares students for more complex subtraction.

Place Value Chart:

Take This Quiz:

Addition and Subtraction Quiz: MCQ Exam!

Working with Two-Digit and Three-Digit Numbers

As students get more confident, they will add and subtract numbers with two or three digits. The steps are the same, but we now have to remember place value and sometimes use carrying or borrowing.

Two-digit numbers (like 45 or 55) involve tens and ones. Adding or subtracting them means working from right to left. With three-digit numbers (like 108), we include hundreds too.

Steps for Two-Digit and Three-Digit Numbers:

1. Line up numbers by place value
2. Start with ones
3. Move to tens, then hundreds
4. If needed, carry over or borrow

Word Problems and Examples

Adding and subtracting are part of everyday life. Whether you are at the store, playing with toys, or sharing with friends, these math skills help you make sense of the world.

Real-life problems help students apply what they've learned in meaningful ways. While solving such problems, students should read carefully, look for key information, and decide whether they need to add or subtract.

Important Clues in Word Problems: