Dividing Fractions: Keep, Change, Flip
6-8
1
Evaluating Algebraic Expressions
Lesson Details
Grade Level
6-8
Duration (minutes)
2
Summary
A grade 6-8 math lesson teaching how to evaluate algebraic expressions using substitution — substitute, multiply, then add or subtract — with three worked examples, including one with two variables.
Student Worksheet: Evaluating Algebraic Expressions
Teacher Note: Students can watch the video lesson above and answer the questions. Click the “Teacher Answer Key” dropdown below when you are ready to review the solutions!
Key Concepts:
• Evaluate: Find the value of an expression after substituting numbers for the variables.
• The Process: Substitute, multiply, then add or subtract.
• Order Matters: Always multiply before adding or subtracting.
Instructions: Read each question carefully and write your answer in the space provided.
- Question 1: Evaluate 3x + 2 when x = 4.
- Question 2: Evaluate 5x − 3 when x = 6.
- Question 3: Evaluate 2x + 3y when x = 2 and y = 5.
- Question 4: In the process, which step comes first: substituting or multiplying?
- Question 5: Why should you multiply before subtracting in an expression like 5x − 3?
Click to reveal Teacher Answer Key
1. 14
2. 27
3. 19
4. Substituting comes first
5. Because the order of operations requires multiplication before subtraction
Disclaimer: This worksheet was generated with AI assistance based on original video content. It is intended for educational reference only. Teachers are encouraged to review and adjust questions to fit their curriculum standards before classroom use.
🎯 Extension Activity: Give students a new expression, like 4x − 2y, and two values (x = 5, y = 3). Have them substitute, multiply, and subtract on their own to find the value.