Warm-Up 1
Day 9: Expressions and Geometry
Preview variables and equations while reviewing area, volume, and formulas.
Student Goal
I can write and evaluate simple expressions and use formulas to solve problems.
Why It Matters
Expressions and formulas give students a way to describe patterns, unknowns, area, and volume clearly.
Warm-Up
Warm-Up 2
Evaluate n + 5 when n = 8.
Warm-Up 3
What does a variable stand for?
Short Lesson
Standard Focus:
NC.6.EE: Expressions and Equations
Student-Friendly Standard Goal:
I can use expressions, equations, and geometry formulas to represent and solve problems.
- A variable is a letter that stands for a number.
- To evaluate an expression, replace the variable with the given number and calculate carefully.
- Formulas are reusable plans. For example, the area of a rectangle is A = l x w.
Guided Examples
Guided Example 1
Use a Volume Formula
A rectangular prism has length 5, width 3, and height 2. What is its volume?
Step 1
V = l x w x h
Which numbers should be substituted?
Guided Example 2
Evaluate an Expression
Evaluate 2x + 1 when x = 5.
Step 1
2x + 1
What should replace x?
Practice
Problem 1
Evaluate x + 9 when x = 6.
Problem 2
Evaluate 4n when n = 7.
Problem 3
Solve m + 8 = 20.
Problem 4
True or false: The area of a rectangle is length times width.
Problem 5
Find the area of a triangle with base 8 and height 6. Use A = 1/2bh.
Reflection
How are you feeling about today's skill?
Optional reflection: Optional prompt: How can a formula help you solve a problem?