Back To Course

6th-8th Grade Math: Practice & Review55 chapters | 469 lessons

Are you a student or a teacher?

Try Study.com, risk-free

As a member, you'll also get unlimited access to over 75,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.

Try it risk-freeWhat teachers are saying about Study.com

Already registered? Login here for access

Your next lesson will play in
10 seconds

Lesson Transcript

Instructor:
*Yuanxin (Amy) Yang Alcocer*

Amy has a master's degree in secondary education and has taught math at a public charter high school.

After viewing this lesson, you should be able to identify shapes that have a line of symmetry in them and know how to find where this line is. A short quiz to test your knowledge will follow the lesson.

In this lesson, we will talk about geometric shapes. **Geometric shapes** are, simply, shapes without any math attached to them. For example, if you see a circle drawn on a billboard, then you are looking at a geometric shape. If you see triangles, squares, octagons, or any other shape that you know, then you are looking at a geometric shape. Even curvy shapes are geometric shapes. The shape that the shadow of a dog makes is a geometric shape.

Yes, we see geometric shapes all around us. In this lesson, though, we are limiting the shapes that we are going to talk about. We are limiting them to the shapes that have a line of symmetry in them.

This **line of symmetry** is the line in the shape that splits the shape in half so that each half is the mirror image of the other. For example, the line of symmetry in a circle is one that cuts the circle in half and goes through the center of the circle. When you fold your circle along this line, you will find that the halves match up perfectly.

Geometric shapes can have more than one line of symmetry. How many does our circle have? A good way to find out is to start folding the circle in different ways. Remember, you want your halves to match up perfectly. How many different ways can you fold the circle so that the halves match up perfectly? You will find that a circle can be folded in many ways - actually, anywhere, as long as we go through the center of the circle. This tells us that the circle has an infinite number of lines of symmetry.

Let's look at a couple more shapes and see about their lines of symmetry.

Let's look at the rectangle. How can we fold the rectangle so that the halves match up perfectly? Well, we can fold it sideways in half. Can we fold it another way? Yes, we can. We can also fold it in half either going up or going down.

Can we fold it yet another way? Hmm, it doesn't look like it. If we tried to fold it diagonally, we'd find that the halves don't match up perfectly; they actually overlap in certain areas. What does this tell us? It tells us that a rectangle has two lines of symmetry.

Now, let's look at a more complicated shape. Let's look at the capital letter *A*. Does this geometric shape have a line of symmetry? Imagine folding it in different ways. Is there a way you can fold it in half so that the halves match up perfectly? Yes, there is. Which way is this? If you fold it in half sideways, you will see that both halves will match up perfectly. Is there another way? No. So, the capital letter *A* has one line of symmetry.

There are many other shapes that have lines of symmetry. Start folding and you will discover more of them.

Let's review what we've learned. We learned that **geometric shapes** are simply shapes without any math attached to them. A **line of symmetry** is the line in the shape that splits the shape in half so that each half is the mirror image of the other.

A geometric shape can have more than one line of symmetry. A circle, for example, has an infinite number of lines of symmetry. To find lines of symmetry, fold your shape in half in different ways. When your shape folds in half and the halves match up perfectly, you have found a line of symmetry.

After you finish this lesson, you should have the ability to:

- Explain what geometric shapes are
- Define line of symmetry
- Utilize examples to figure out lines of symmetry

To unlock this lesson you must be a Study.com Member.

Create your account

Are you a student or a teacher?

Already a member? Log In

BackWhat teachers are saying about Study.com

Already registered? Login here for access

Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

You are viewing lesson
Lesson
1 in chapter 42 of the course:

Back To Course

6th-8th Grade Math: Practice & Review55 chapters | 469 lessons

- What is a Line of Symmetry in Geometric Shapes? 3:19
- Similarity in Geometric Shapes 6:03
- Parallel, Perpendicular and Transverse Lines 6:06
- Identifying Parallel Lines in Geometric Shapes 3:35
- Constructing Perpendicular Lines in Geometry 3:39
- Identifying Perpendicular Lines in Geometric Shapes 3:54
- What is Symmetry in Math? - Definition & Concept 2:54
- Go to 6th-8th Grade Geometry: Symmetry, Similarity & Congruence

- Computer Science 109: Introduction to Programming
- Introduction to HTML & CSS
- Introduction to JavaScript
- Computer Science 332: Cybersecurity Policies and Management
- Introduction to SQL
- Progressive Politics & American Imperialism
- Reconstruction, Westward Expansion, Industrialization & Urbanization
- North America & the 13 Colonies
- The Renaissance & The Age of Exploration
- Algorithmic Analysis, Sorting & Searching
- CEOE Test Cost
- PHR Exam Registration Information
- Claiming a Tax Deduction for Your Study.com Teacher Edition
- What is the PHR Exam?
- Anti-Bullying Survey Finds Teachers Lack the Support They Need
- What is the ASCP Exam?
- ASCPI vs ASCP

- Convergent Sequence: Definition, Formula & Examples
- Mauryan Empire Art & Culture
- Multi-Dimensional Arrays in C Programming: Definition & Example
- Tests for Identifying Common Gases
- Singing Lesson Plan
- Arrays & Strings in JavaScript: Conversion & String Methods
- Heuristic Methods in AI: Definition, Uses & Examples
- Quiz & Worksheet - Average & Instantaneous Rates of Change
- Quiz & Worksheet - Speed, Velocity & Acceleration
- Quiz & Worksheet - Functions & Parameters Overview
- Quiz & Worksheet - Incremental & Radical Change
- Flashcards - Measurement & Experimental Design
- Flashcards - Stars & Celestial Bodies
- NGSS | Next Generation Science Standards Guide for Teachers
- 10th Grade Math Worksheets & Printables

- 10th Grade English: Tutoring Solution
- Praxis Business Education - Content Knowledge (5101): Practice & Study Guide
- DSST A History of the Vietnam War: Study Guide & Test Prep
- AP European History: Tutoring Solution
- NY Regents Exam - Integrated Algebra: Test Prep & Practice
- ILTS Business, Marketing, and Computer Education Flashcards
- Vocal Range
- Quiz & Worksheet - Kinds of Proposals
- Quiz & Worksheet - Factoring a Problem Through Division
- Quiz & Worksheet - Hypothesis, Theory & Law in Science
- Quiz & Worksheet - Overview of Genetic Engineering
- Quiz & Worksheet - Using Quotes & Paraphrasing to Avoid Plagiarism

- Oceanic Ridge System: Formation & Distribution
- Authors Like Cormac McCarthy
- Script Writing Prompts
- How to Study for a Placement Test for College
- Life Science Projects
- Unrest in Vietnam During the Eisenhower Years: Learning Objectives & Activities
- Earth Science Projects for Middle School
- Scientific Method Experiments for Kids
- Free ACT Math Practice
- Analytical Reasoning Questions on the LSAT
- How Hard is the GMAT?
- Persuasive Writing Prompts

- Tech and Engineering - Videos
- Tech and Engineering - Quizzes
- Tech and Engineering - Questions & Answers

Browse by subject