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- Grade 4 Math
- 2D Shapes and Planes

Still Confused?

Try reviewing these fundamentals first

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Get Started NowStart now and get better math marks!

Get Started NowStart now and get better math marks!

Get Started NowStart now and get better math marks!

Get Started Now- Intro Lesson: a4:02
- Intro Lesson: b3:05
- Intro Lesson: c5:55
- Intro Lesson: d7:35
- Lesson: 1a1:51
- Lesson: 1b4:12
- Lesson: 1c2:31
- Lesson: 1d1:26
- Lesson: 2a1:14
- Lesson: 2b2:54
- Lesson: 2c1:30
- Lesson: 2d1:48
- Lesson: 2e1:18
- Lesson: 2f2:19
- Lesson: 3a3:08
- Lesson: 3b1:58
- Lesson: 3c2:42
- Lesson: 4a3:02
- Lesson: 4b4:12
- Lesson: 4c10:09
- Lesson: 5a8:05
- Lesson: 5b4:05
- Lesson: 5c4:53

In this lesson, we will learn:

- How to identify symmetrical vs. asymmetrical shapes or pictures
- How to check symmetry lines with the folding method or mirror test method

- A "
**symmetrical**" shape is made up of exact same parts facing each other - A
**line of symmetry**divides a symmetrical shape into 2**congruent**parts - If the shape is not symmetrical it is "
**asymmetrical**"

- Check if a shape has a
**line of symmetry**by**folding it in half**to see if the parts match up

- or using a
**mirror test**: laying the picture/shape flat and putting a mirror on a possible symmetry line to see if the mirrored image matches with the original

- Some shapes
*have more than one*line of symmetry.**Regular polygons**have the same number of symmetry lines as number of sides - some words (alphabet letters) and numbers also have symmetry:

Ex. triangles = 3 sides = 3 symmetry lines

- IntroductionIntroduction to Basics of Symmetry:a)What is symmetry? What is a symmetrical shape?b)Folding test for lines of symmetryc)Mirror test for lines of symmetryd)Symmetry in alphabet letters and numbers
- 1.
**Congruent parts and lines of symmetry**

A dotted line breaks the shape into two parts.- Is it a line of symmetry?
- Are the parts congruent?

a)b)c)d) - 2.
**Line of symmetry**

Draw a line of symmetry for the shape.a)b)c)d)e)f) - 3.
**Multiple lines of symmetry**

Draw two possible lines of symmetry.a)b)c) - 4.
**Symmetrical shapes on a dot grid**

Using the dot grid, finish drawing the shape. The line of symmetry and half of the shape are shown.a)b)c) - 5.
**Symmetry of regular polygons**a)For each regular polygon, draw all possible lines of symmetry and fill out your answers in the table.b)Following the pattern for regular polygons, how many lines of symmetry would a heptagon have?c)Following the pattern for regular polygons, how many lines of symmetry would an octagon have?