Grade 2
  1. Number Sense and Operations  1.1. Counting and Number Sequences  1.1.1. Counting up to 100  1.1.2. Counting by 2s, 5s, and 10s  1.1.3. Counting Backward from 20  1.1.4. Odd and even numbers in counting sequences  1.2. Place Value  1.2.1. Understanding ones and tens  1.2.2. Comparing Two-Digit Numbers  1.2.3. Identifying the Value of Each Digit in a Number  1.2.4. Building numbers using tens and ones  1.3. Addition and Subtraction  1.3.1. Basic addition up to 20  1.3.2. Basic subtraction up to 20  1.3.3. Addition with Regrouping  1.3.4. Subtraction with Borrowing  1.3.5. Solving word problems involving addition and subtraction  1.3.6. Addition and Subtraction with Multiples of 10  1.4. Odd and Even Numbers  1.4.1. Identifying Odd and Even Numbers  1.4.2. Understanding patterns in odd and even numbers  1.4.3. Simple operations with odd and even numbers
  2. Fractions and Decimals  2.1. Introduction to Fractions  2.1.1. Understanding halves and quarters  2.1.2. Representing fractions visually  2.1.3. Simple Fraction Comparisons  2.1.4. Writing Simple Fractions  2.1.5. Fractions as part of a whole  2.2. Fraction Equivalency  2.2.1. Understanding Equal Parts  2.2.2. Identifying Equivalent Fractions
  3. Measurement and Data  3.1. Length Measurement  3.1.1. Measuring objects using rulers  3.1.2. Comparing lengths  3.1.3. Estimating lengths  3.1.4. Understanding units of measurement (centimeters and inches)  3.1.5. Relating Length Measurements to Real-World Objects  3.2. Weight and Mass Measurement  3.2.1. Comparing Weights of Objects  3.2.2. Estimating weight in grams and kilograms  3.2.3. Using balance scales for comparison  3.3. Volume and Capacity Measurement  3.3.1. Understanding capacity with cups and liters  3.3.2. Comparing capacities of containers  3.3.3. Introduction to Milliliters  3.4. Time  3.4.1. Reading analog and digital clocks  3.4.2. Understanding hours and minutes  3.4.3. Calculating elapsed time in hours  3.4.4. Days of the week and months of the year  3.4.5. Understanding AM and PM  3.5. Money  3.5.1. Recognizing coins and bills  3.5.2. Counting money up to $1  3.5.3. Simple Addition and Subtraction with Money  3.5.4. Making Change for a Dollar
  4. Geometry and Spatial Reasoning  4.1. Shapes and Their Attributes  4.1.1. Identifying basic shapes (circle, triangle, square, rectangle)  4.1.2. Understanding sides and corners  4.1.3. Distinguishing between 2D and 3D shapes  4.1.4. Recognizing 3D Shapes (Cube, Sphere, Cone, Cylinder)  4.1.5. Composing and Decomposing Shapes  4.2. Symmetry  4.2.1. Understanding Lines of Symmetry  4.2.2. Drawing Symmetrical Shapes  4.2.3. Identifying Symmetrical Objects in the Environment  4.3. Patterns and Spatial Awareness  4.3.1. Recognizing and Creating Patterns  4.3.2. Extending Patterns  4.3.3. Understanding positions (left, right, above, below)  4.3.4. Using a grid to locate objects
  5. Data Handling and Probability  5.1. Collecting and Organizing Data  5.1.1. Using tally marks  5.1.2. Reading Bar Graphs  5.1.3. Simple Pictographs  5.1.4. Creating Bar Graphs from Given Data  5.2. Interpreting Data  5.2.1. Answering questions based on data  5.2.3. Identifying Most and Least in Data Sets  5.3. Introduction to Probability  5.3.1. Understanding likely and unlikely events

Grade 2 → Number Sense and Operations → Addition and Subtraction ↓


Basic subtraction up to 20


Subtraction is one of the fundamental operations in math, and it involves subtracting one number from another. In this explanation, we will explore basic subtraction up to 20, which is an essential skill for young learners. Understanding subtraction lays the foundation for more advanced mathematical concepts.

What is subtraction?

Subtraction is the process of removing items from a group. It helps us find the difference between numbers. For example, if you have 10 apples and you're given 3, you can find out how many apples are left by subtracting 3 from 10:

10 - 3 = 7

Key Terms in Subtraction

Before we dive deeper into subtraction, let's understand some key terms:

  • Minus sign (-): This symbol indicates subtraction.
  • Minuend: The number you subtract. In 10 - 3 = 7, the minuend is 10.
  • Subtraction: The numbers you subtract. In 10 - 3 = 7, the subtractee is 3.
  • Difference: The result of a subtraction. In 10 - 3 = 7, the difference is 7.

Visual representation of subtraction

Using visuals can make subtraction easier to understand. Let's look at some examples:

Example: Subtract 5 from 12

    12 - 5 = 7
7

Counting backwards

One way to perform subtraction is to count backwards. Let's consider an example: subtracting 4 from 9. Start at 9 and count backwards 4 times:

  1. Start at 9.
  2. One step back: 8.
  3. Two steps back: 7.
  4. Three steps back: 6.
  5. Four steps back: 5.

Therefore, 9 - 4 = 5.

Use of number lines

The number line is a useful tool for visualizing subtraction. Below is how you can use the number line for subtraction:

Example: Subtracting 3 from 8

0 1 2 3 4 5 8 5

Start at 8 and move 3 steps to the left to reach 5, which shows that 8 - 3 = 5.

Text Example

Let's look at some more text examples to further strengthen your understanding:

Example 1: Subtracting small numbers

Imagine you have 7 candies and you eat 2 candies. How many candies do you have left?

7 - 2 = 5

You have 5 candies left.

Example 2: Subtracting from zero

Subtracting zero does not change the number. If there are 10 birds on the tree and none of them fly away, how many birds are there in total?

10 - 0 = 10

All 10 birds are still on the tree.

Example 3: Subtracting to make zero

What happens if you have 6 apples and you give them all away? How many apples will you have now?

6 - 6 = 0

You have zero apples.

Practice makes perfect

The best way to master subtraction is to practice. Solve these problems to hone your skills:

Problem 1: John has 15 marbles, and he gives 4 marbles to his friend. How many marbles does he have now?

15 - 4 = 11

Problem 2: Emily has 9 pencils, and she loses 2. How many pencils are left?

9 - 2 = 7

Additional Tips

Here are some tips for becoming proficient at basic subtraction:

  • Memorize basic subtraction facts: Just as with addition, knowing basic subtraction facts helps you solve problems more quickly.
  • Use manipulatives: Physical objects like counters or blocks can help demonstrate subtraction.
  • Practice mental math: Practice subtraction mentally to improve your calculation speed and accuracy.

Conclusion

Basic subtraction up to 20 is an essential skill in early math. By understanding the concepts of subtraction, using visual aids like number lines, and practicing with problems, young learners can develop a strong foundation. Over time, subtraction becomes an easy and automatic process. Keep practicing, and you'll master this skill!


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Basic addition up to 20
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Basic subtraction up to 20

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