Nigeria - Primary 1 - General Mathematics - Subtraction I

Nigeria - Primary 1 - General Mathematics - Subtraction I

Lessonotes Nigeria curriculum lesson video for Primary 1 General Mathematics. This lesson focuses on Subtraction I for classroom teaching, revision, and home learning.

Country: Nigeria
Grade: Primary 1
Subject: General Mathematics
Scheme: Lessonotes Curriculum
Theme: Basic Operations
Period: Term 1
Week: 8

Performance Objectives
1. subtract from whole numbers not greater than 9;
2. subtract from whole numbers not greater than 18;
3. crosscheck accuracy in subtraction.

Lesson Content
Grade / Level: Primary 1
Subject: General Mathematics
Theme: Basic Operations
Topic: Subtraction I
Term: 1st Term
Week: 8

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### 1. Overview and Learning Objectives

This topic introduces Primary 1 learners to the fundamental concept of subtraction. Subtraction is a crucial basic operation in mathematics that involves 'taking away' a certain quantity from another, finding the difference, or determining how much is left. It is an essential skill that learners will encounter and use daily in various real-life scenarios within the Nigerian context, such as managing pocket money, sharing items with siblings, or calculating remaining food items. Mastery of subtraction at this foundational level prepares learners for more complex mathematical operations.

**Specific Learning Objectives:**
Upon completion of this lesson, students will be able to:
1. Take away objects from a given group of up to 9 items and state the number remaining.
2. Subtract a smaller number from a larger number, where the larger number is not more than 18.
3. Check their subtraction answers to confirm accuracy using simple methods.

**Connection to Real-World Applications in Nigeria:**
* **Market Transactions:** Calculating how much change is left after buying items like akara, groundnuts, or mangoes at the local market.
* **Sharing and Distribution:** Determining how many slices of yam remain after some have been eaten, or how many pieces of biscuit are left after sharing with friends.
* **Counting Resources:** Keeping track of farm produce, livestock, or classroom materials by removing used or sold items.

### 2. Key Concepts and Explanations

**A. What is Subtraction?**
Subtraction is the process of taking one number or quantity away from another. It tells us how many are left, the difference between two numbers, or how much less one number is than another.
* **Keywords:** 'Take away', 'minus', 'difference', 'fewer', 'how many left', 'subtract'.
* **Symbol:** The minus sign (–) is used to represent subtraction. For example, 5 – 2 means "5 take away 2".

**B. Components of a Subtraction Problem (Simplified for Primary 1)**
While formal terms like 'minuend', 'subtrahend', and 'difference' might be too advanced, teachers should ensure students understand:
* **The starting number:** The total amount one begins with (e.g., "You have 7 mangoes").
* **The number to be taken away:** The quantity that is removed (e.g., "You eat 2 mangoes").
* **The result/remaining number:** What is left after taking away (e.g., "How many mangoes are left?").

**C. Methods for Subtraction (Practical for Nigerian Classrooms)**

1. **Using Concrete Objects:** This is the most effective method for Primary 1.
* **Procedure:** Teacher presents a group of objects (e.g., counting sticks, bottle tops, pebbles, seeds, fruits). Students count the total. Teacher then physically removes a specified number of objects. Students count the remaining objects.
* **Example:** Teacher places 6 stones on the table. "We have 6 stones. Take away 2 stones." Students remove 2 stones. "How many stones are left?" Students count the remaining 4 stones. So, 6 – 2 = 4.

2. **Using Fingers:** Useful for smaller numbers.
* **Procedure:** Students raise the number of fingers representing the starting number. They then fold down the number of fingers to be subtracted. They count the remaining raised fingers.
* **Example:** For 9 – 4: Students raise 9 fingers. They fold down 4 fingers. They count the 5 remaining raised fingers. So, 9 – 4 = 5.

3. **Drawing Pictures/Tally Marks:** A visual representation method.
* **Procedure:** Students draw circles, squares, or tally marks to represent the starting number. They then cross out the number of items to be subtracted. They count the uncrossed items.
* **Example:** For 7 – 3: Students draw 7 circles: O O O O O O O. They cross out 3 circles: X X X O O O O. They count the 4 remaining circles. So, 7 – 3 = 4.

4. **Counting Backwards:** Mentally or using a number line (if available/introduced).
* **Procedure:** Starting from the larger number, students count backwards the number of steps to be subtracted.
* **Example:** For 8 – 3: Students start at 8 and count backwards 3 steps: 7, 6, 5. The answer is 5. So, 8 – 3 = 5.

**D. Subtraction from Whole Numbers Not Greater Than 9**
This involves applying the methods above to problems where the initial number is 9 or less.
* **Worked Example 1 (Using Objects/Finger

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