Addition and Subtraction of Directed Numbers Mathematics JSS 1

Lesson Plan: Addition and Subtraction of Directed Numbers

Subject: Mathematics

Class: JSS 1

Term: Second Term

Week: 8

Age: 10 – 12 years

Topic: Addition and Subtraction of Directed Numbers

Sub-topic: Understanding and Applying Directed Numbers on a Number Line

Duration: 40 minutes

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Behavioral Objectives:

By the end of the lesson, students should be able to:

1. Define directed numbers.
2. Identify positive and negative numbers on a number line.
3. Add directed numbers correctly using a number line.
4. Subtract directed numbers correctly using a number line.
5. Solve real-life problems involving directed numbers.

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Keywords:

• Directed numbers – Numbers that have a sign, either positive (+) or negative (-).
• Positive numbers – Numbers greater than zero.
• Negative numbers – Numbers less than zero.
• Number line – A straight line that shows numbers in order, from negative to positive.
• Addition – The process of finding the sum of two or more numbers.
• Subtraction – The process of finding the difference between two numbers.

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Set Induction:

The teacher asks students:

• “What happens when you move forward on a staircase?”
• “What happens when you step backward?”
• “Can we apply this idea to numbers?”

The teacher then draws a number line on the board and explains how numbers can move forward (addition) and backward (subtraction).

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Entry Behavior:

Students already know how to count forward and backward on a number line with whole numbers.

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Learning Resources and Materials:

• Number line chart
• Counters or small stones
• Flashcards with positive and negative numbers
• Chalk and board

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Building Background/Connection to Prior Knowledge:

Students have previously learned about whole numbers and their position on a number line. This lesson extends their knowledge by introducing negative numbers and showing how to add and subtract them.

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Embedded Core Skills:

• Numeracy: Understanding positive and negative numbers.
• Critical Thinking: Applying rules of addition and subtraction in real-life scenarios.
• Problem-Solving: Solving mathematical problems using directed numbers.

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Reference Books:

• Lagos State Scheme of Work
• New General Mathematics for JSS 1
• Essential Mathematics for JSS 1

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Instructional Materials:

• Number line drawn on the board
• Markers or chalk
• Flashcards with different numbers
• Real-life scenarios (e.g., temperature changes, bank transactions)

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Content: Addition and Subtraction of Directed Numbers

Definition of Directed Numbers

Directed numbers are numbers that have a positive (+) or negative (-) sign.

• Positive numbers (+): Numbers greater than zero (e.g., +3, +5, +10).
• Negative numbers (-): Numbers less than zero (e.g., -2, -6, -9).

On a number line:

• Numbers to the right of zero are positive.
• Numbers to the left of zero are negative.

Rules for Addition and Subtraction of Directed Numbers

1. Adding a positive number (+) → Move right on the number line.
2. Adding a negative number (-) → Move left on the number line.
3. Subtracting a positive number (+) → Move left on the number line.
4. Subtracting a negative number (-) → Move right on the number line.

Examples of Adding and Subtracting Directed Numbers

1. Addition:

   • (+3) + (+2) = +5 (Move 2 steps right from +3)
   • (-4) + (+3) = -1 (Move 3 steps right from -4)
   • (-2) + (-5) = -7 (Move 5 steps left from -2)

2. Subtraction:

   • (+6) – (+4) = +2 (Move 4 steps left from +6)
   • (-3) – (+2) = -5 (Move 2 steps left from -3)
   • (-6) – (-3) = -3 (Move 3 steps right from -6)

Real-Life Applications of Directed Numbers

• Temperature changes (e.g., from 5°C to -3°C).
• Bank transactions (e.g., deposit = positive, withdrawal = negative).
• Movement in elevators (e.g., going up = positive, going down = negative).

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Evaluation: Fill-in-the-Blank Questions

1. Directed numbers have either a ______ or ______ sign.
   a) Blue, Red
   b) Positive, Negative
   c) Large, Small
   d) None of the above

2. The number to the right of zero on a number line is always ______.
   a) Negative
   b) Neutral
   c) Positive
   d) Undefined

3. When adding a negative number, you move ______ on a number line.
   a) Right
   b) Left
   c) Up
   d) Down

4. (-4) + (+6) = ______
   a) -10
   b) +2
   c) 0
   d) -2

5. What is the result of (-8) + (+4)?
   a) -12
   b) -4
   c) +4
   d) +12

6. Subtracting a negative number is the same as ______.
   a) Moving right on the number line
   b) Moving left on the number line
   c) Multiplying by zero
   d) None of the above

7. (+10) – (+5) = ______
   a) +15
   b) -5
   c) +5
   d) 0

8. When you add two negative numbers, the result is always ______.
   a) Positive
   b) Negative
   c) Zero
   d) Undefined

9. The opposite of +7 on a number line is ______.
   a) -7
   b) 0
   c) +7
   d) -14

10. (-2) – (+3) = ______
    a) -5
    b) +1
    c) +5
    d) -1

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Class Activity Discussion: FAQs with Answers

1. What are directed numbers?
   Directed numbers are numbers with a positive (+) or negative (-) sign.

2. Why do we use directed numbers?
   They help represent real-life situations like temperature, debts, and heights.

3. How do you add two negative numbers?
   Add their absolute values and keep the negative sign.

4. How do you subtract a negative number from a positive number?
   Subtracting a negative number is the same as adding its positive equivalent.

5. What happens when you add a positive and a negative number?
   The result depends on their absolute values; subtract the smaller from the larger and take the sign of the larger number.

6. How do you represent -5 on a number line?
   -5 is five steps to the left of zero.

7. What is the sum of -6 and -3?
   The sum is -9 because adding two negative numbers results in a more negative number.

8. Why do we move left when subtracting on a number line?
   Moving left represents decreasing a value, just like in real-life cases such as losing money.

9. Can two numbers with different signs add up to zero?
   Yes, if they are equal in absolute value, such as +7 and -7.

10. If you subtract -4 from -2, what do you get?
    You get (+2) because subtracting a negative number is like adding its positive counterpart.

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Presentation Steps

1. The teacher revises the previous topic (Number System).
2. The teacher introduces the new topic using real-life examples.
3. The teacher allows students to contribute, correcting them where necessary.

Teacher’s Activities

• Explain the concept using a number line.
• Demonstrate addition and subtraction of directed numbers.
• Give students real-life scenarios to solve.

Learners’ Activities

• Observe teacher demonstrations.
• Practice adding and subtracting directed numbers.
• Solve exercises on the board.

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Evaluation Questions (Short Answer Format)

1. Define directed numbers.
2. What is the rule for subtracting a negative number?
3. Solve: (-7) + (+3) = ?
4. Solve: (+5) – (-2) = ?
5. What happens when you subtract a positive number?
6. Find the result of (-5) + (+8).
7. What is the difference between -12 and -7?
8. Solve: (-9) – (-3) = ?
9. If you move 3 steps left from -2 on the number line, where will you land?
10. Explain why subtracting a negative number is the same as adding.

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Conclusion:

The teacher marks students’ work and provides feedback.

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Mid Term Test Mathematics JSS 1 Second Term Lesson Notes