Lesson Notes By Weeks and Term v4 - JHS 1
Algebraic Expressions
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Algebraic Expressions
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Subject: Mathematics
Class: JHS 1
Term: 2nd Term
Week: 10
Grade code: B7.2.2.1.4
Strand code: 2
Sub-strand code: 2
Content standard code: B7.2.2.1
Indicator code: B7.2.2.1.4
Theme: ALGEBRA
Subtheme: Algebraic Expressions
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This lesson introduces learners to a fundamental skill in algebra: evaluating algebraic expressions. We will learn how to replace variables (the letters in maths) with specific numbers and then calculate the final value. This skill is like having a recipe or a formula; if you know the ingredients (the values), you can work out the final result. In Ghana, this is useful for everything from calculating the cost of items at the market, to understanding mobile money charges, or even figuring out the materials needed for a small building project. It is a building block for more advanced mathematics and science.
A. Recap of Key Terms Algebraic Expression: A mathematical phrase that contains numbers, variables, and operation signs (+, -, ×, ÷). Example: `3x + 5` Variable: A letter that represents an unknown number. Its value can change. Example: In `a + 4`, 'a' is the variable. Constant: A number on its own. Its value does not change. Example: In `a + 4`, '4' is the constant. Substitution: This is the action of replacing a variable with a specific number. Think of it like a substitute player in a football match; one person comes out, and another goes in to take their exact position. Evaluation: This is the action of calculating the final numerical answer of an expression after substitution has been done. B. The Process of Substitution and Evaluation To evaluate an algebraic expression, we follow a simple, two-step process: Substitute: Replace every variable with its given value. A very good habit is to put the value in brackets `( )` when you substitute. This prevents common mistakes, especially with multiplication and negative numbers. Evaluate: Use the rules of BODMAS to simplify the expression and find the single numerical answer.
BODMAS Reminder: Brackets Of (or Orders, like powers/exponents) Division Multiplication Addition Subtraction *(Remember: Division and Multiplication are done from left to right. Addition and Subtraction are also done from left to right.)*
C. Worked Examples
Example 1: A Simple Expression Evaluate the expression `y + 8` if `y = 5`. Step 1: Substitute Write down the original expression: `y + 8` Replace the variable `y` with its value, `5`. It becomes: `5 + 8` Step 2: Evaluate Perform the addition. `5 + 8 = 13` Answer: When `y = 5`, the expression `y + 8` evaluates to `13`.