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
Behavioral Objectives:
By the end of the lesson, students should be able to:
- Define directed numbers.
- Identify positive and negative numbers on a number line.
- Add directed numbers correctly using a number line.
- Subtract directed numbers correctly using a number line.
- Solve real-life problems involving directed numbers.
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.
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).
Entry Behavior:
Students already know how to count forward and backward on a number line with whole numbers.
Learning Resources and Materials:
- Number line chart
- Counters or small stones
- Flashcards with positive and negative numbers
- Chalk and board
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.
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.
Reference Books:
- Lagos State Scheme of Work
- New General Mathematics for JSS 1
- Essential Mathematics for JSS 1
Instructional Materials:
- Number line drawn on the board
- Markers or chalk
- Flashcards with different numbers
- Real-life scenarios (e.g., temperature changes, bank transactions)
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
- Adding a positive number (+) → Move right on the number line.
- Adding a negative number (-) → Move left on the number line.
- Subtracting a positive number (+) → Move left on the number line.
- Subtracting a negative number (-) → Move right on the number line.
Examples of Adding and Subtracting Directed Numbers
-
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)
-
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).
Evaluation: Fill-in-the-Blank Questions
-
Directed numbers have either a ______ or ______ sign.
a) Blue, Red
b) Positive, Negative
c) Large, Small
d) None of the above -
The number to the right of zero on a number line is always ______.
a) Negative
b) Neutral
c) Positive
d) Undefined -
When adding a negative number, you move ______ on a number line.
a) Right
b) Left
c) Up
d) Down -
(-4) + (+6) = ______
a) -10
b) +2
c) 0
d) -2 -
What is the result of (-8) + (+4)?
a) -12
b) -4
c) +4
d) +12 -
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 -
(+10) – (+5) = ______
a) +15
b) -5
c) +5
d) 0 -
When you add two negative numbers, the result is always ______.
a) Positive
b) Negative
c) Zero
d) Undefined -
The opposite of +7 on a number line is ______.
a) -7
b) 0
c) +7
d) -14 -
(-2) – (+3) = ______
a) -5
b) +1
c) +5
d) -1
Class Activity Discussion: FAQs with Answers
-
What are directed numbers?
Directed numbers are numbers with a positive (+) or negative (-) sign. -
Why do we use directed numbers?
They help represent real-life situations like temperature, debts, and heights. -
How do you add two negative numbers?
Add their absolute values and keep the negative sign. -
How do you subtract a negative number from a positive number?
Subtracting a negative number is the same as adding its positive equivalent. -
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. -
How do you represent -5 on a number line?
-5 is five steps to the left of zero. -
What is the sum of -6 and -3?
The sum is -9 because adding two negative numbers results in a more negative number. -
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. -
Can two numbers with different signs add up to zero?
Yes, if they are equal in absolute value, such as +7 and -7. -
If you subtract -4 from -2, what do you get?
You get (+2) because subtracting a negative number is like adding its positive counterpart.
Presentation Steps
- The teacher revises the previous topic (Number System).
- The teacher introduces the new topic using real-life examples.
- 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.
Evaluation Questions (Short Answer Format)
- Define directed numbers.
- What is the rule for subtracting a negative number?
- Solve: (-7) + (+3) = ?
- Solve: (+5) – (-2) = ?
- What happens when you subtract a positive number?
- Find the result of (-5) + (+8).
- What is the difference between -12 and -7?
- Solve: (-9) – (-3) = ?
- If you move 3 steps left from -2 on the number line, where will you land?
- Explain why subtracting a negative number is the same as adding.
Conclusion:
The teacher marks students’ work and provides feedback.
Mid Term Test Mathematics JSS 1 Second Term Lesson Notes
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