Screen Classroom

📐 Perimeter Concepts

Master perimeter basics, formulas, calculations, and real-world applications

📚

Perimeter Basics

Understanding what perimeter is and how to measure it

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Shape Formulas

Learn perimeter formulas for different geometric shapes

🧮

Perimeter Calculator

Interactive tool to calculate perimeters of various shapes

📝

Word Problems

Solve real-world perimeter problems step by step

🏆

Mastery Quiz

Test your perimeter knowledge with 15 questions

📚 Perimeter Basics

What is Perimeter?

🎯 Understanding Perimeter

Perimeter is the distance around the outside of a shape. Think of it as the length of the boundary or edge of a figure.

Key Concept: Perimeter measures the total length of all sides added together

Real-World Examples

🏠 Around Your Home

• Fencing a yard: How much fence do you need?

• Picture frames: How much trim is needed?

• Garden borders: How much edging to buy?

• Room molding: How much baseboard trim?

🏃‍♂️ Sports & Activities

• Running track: Distance around the track

• Soccer field: Distance around the field

• Swimming pool: Distance around the pool

• Basketball court: Distance around the court

🎨 Arts & Crafts

• Ribbon borders: How much ribbon needed?

• Fabric edges: How much trim to sew?

• Poster borders: How much border tape?

• Cake decorating: How much icing for edges?

🏗️ Construction & Design

• Building foundations: How much concrete?

• Sidewalk borders: How much edging?

• Tile borders: How many border tiles?

• Deck railings: How much railing material?

How to Find Perimeter

📏 The Basic Method

For any shape, perimeter is found by adding up the lengths of all sides.

1

Identify all sides: Count how many sides the shape has

2

Measure each side: Find the length of every side

3

Add them up: Sum all the side lengths together

4

Include units: Don't forget to include the unit of measurement

Units of Measurement

📏 Common Units

Metric System:

• Millimeters (mm) - very small objects

• Centimeters (cm) - small objects

• Meters (m) - rooms, yards

• Kilometers (km) - large areas

📐 Imperial System

US Customary:

• Inches (in) - small objects

• Feet (ft) - rooms, height

• Yards (yd) - sports fields

• Miles (mi) - long distances

Perimeter vs. Other Measurements

🔍 Don't Confuse These!

Perimeter: Distance AROUND a shape (1-dimensional)
Example: How much fence for a garden?

Area: Space INSIDE a shape (2-dimensional)
Example: How much grass seed for a lawn?

Volume: Space INSIDE a 3D object (3-dimensional)
Example: How much water fits in a pool?

💡 Memory Tip

Think "PERimeter = PERimeter of a fence" - it goes around the outside!

Interactive Practice

🎯 Perimeter Identification Practice

What is the perimeter of this shape?

units

🔷 Shape Formulas

Common Shape Formulas

🟩 Rectangle

P = 2l + 2w

Formula: P = 2 × length + 2 × width

Alternative: P = 2(l + w)

Why? Rectangle has 2 long sides and 2 short sides

🟨 Square

P = 4s

Formula: P = 4 × side length

Alternative: P = s + s + s + s

Why? Square has 4 equal sides

🔺 Triangle

P = a + b + c

Formula: P = side a + side b + side c

Note: Works for any triangle (scalene, isosceles, equilateral)

Why? Add up all three sides

⭕ Circle

P = 2πr

Formula: P = 2 × π × radius

Alternative: P = πd (where d = diameter)

Note: π ≈ 3.14159 or use 3.14 for approximations

Special Triangles

🔺 Equilateral Triangle

P = 3s

All three sides are equal, so multiply by 3.

🔺 Isosceles Triangle

P = 2a + b

Two sides are equal (a), plus the base (b).

Irregular Shapes

🔷 Any Polygon

For any shape with straight sides, just add up all the side lengths:

P = 3 + 4 + 5 + 6 + 4 + 3 + 2 = 27 units

💡 Strategy

Label each side length, then add them all up. Don't miss any sides!

Interactive Formula Practice

🎯 Formula Application Practice

What formula should you use for this shape?

🧮 Perimeter Calculator

Interactive Perimeter Calculator

🎯 Choose a Shape to Calculate

Select a shape below and enter its dimensions to calculate the perimeter automatically.

Rectangle Square Triangle Circle

Length: units

Width: units

P = 2l + 2w

Side: units

P = 4s

Side A: units

Side B: units

Side C: units

P = a + b + c

Radius: units

P = 2πr

Quick Reference

📐 Common Formulas

Rectangle: P = 2l + 2w

Square: P = 4s

Triangle: P = a + b + c

Circle: P = 2πr

💡 Calculator Tips

• Enter dimensions as you measure them

• Results update automatically

• Use decimal points for precise measurements

• Check your units match the problem

📝 Word Problems

Solving Perimeter Word Problems

🎯 Problem-Solving Strategy

Follow these steps to solve any perimeter word problem:

1

Read carefully: What shape is described? What are you looking for?

2

Identify the shape: Rectangle, square, triangle, circle, or irregular?

3

Find the dimensions: What measurements are given?

4

Choose the formula: Which perimeter formula applies?

5

Calculate: Substitute values and solve

6

Check your answer: Does it make sense? Include units!

Example Problems

🏠 Example 1: Fencing a Yard

Problem: Sarah wants to put a fence around her rectangular backyard. The yard is 25 feet long and 18 feet wide. How much fencing does she need?

1

Identify: Rectangular yard, need perimeter

2

Dimensions: Length = 25 ft, Width = 18 ft

3

Formula: P = 2l + 2w

4

Calculate: P = 2(25) + 2(18) = 50 + 36 = 86 feet

5

Answer: Sarah needs 86 feet of fencing

🖼️ Example 2: Picture Frame

Problem: A square picture frame has sides that are 8 inches long. How much decorative trim is needed to go around the frame?

1

Identify: Square frame, need perimeter

2

Dimensions: Side = 8 inches

3

Formula: P = 4s

4

Calculate: P = 4(8) = 32 inches

5

Answer: 32 inches of trim is needed

🏃‍♂️ Example 3: Running Track

Problem: A circular running track has a radius of 50 meters. How far does someone run if they complete one lap around the track?

1

Identify: Circular track, need perimeter (circumference)

2

Dimensions: Radius = 50 meters

3

Formula: P = 2πr

4

Calculate: P = 2π(50) = 2 × 3.14 × 50 = 314 meters

5

Answer: One lap is approximately 314 meters

Common Word Problem Types

🏗️ Construction & Building

• Fencing yards or gardens

• Trim around rooms or windows

• Sidewalk or pathway borders

• Foundation measurements

🎨 Arts & Crafts

• Picture frame materials

• Ribbon or lace borders

• Fabric edging

• Decorative trim

🏃‍♂️ Sports & Recreation

• Track and field distances

• Pool or court boundaries

• Game field perimeters

• Walking/jogging paths

🌱 Gardening & Landscaping

• Garden bed borders

• Flower bed edging

• Lawn boundaries

• Planting area perimeters

Interactive Practice

🎯 Word Problem Practice

units

🏆 Perimeter Mastery Quiz

Test Your Perimeter Knowledge

Ready to test your understanding of perimeter concepts? This comprehensive quiz covers all the topics we've learned:

• 15 multiple choice questions

• Covers: Basic concepts, formulas, calculations, and word problems

• Immediate feedback after each question

• Final score and performance breakdown

Question 1 of 15

🎉 Quiz Complete!

85%

13 out of 15 correct

Excellent work! You have mastered perimeter concepts!

4/4

Basic Concepts

4/4

Formulas

3/3

Calculations

3/4

Word Problems