<%@LANGUAGE=VBScript%> Math Matters Level 5 - Chapter 8 - Lesson 5
 
 

Have you noticed that certain shapes or objects match when folded in half? Take for example a magazine or a book, each half matches the other. It would look very funny if a book’s front and back didn’t match when the book is closed!

The reason the front and back of a book matches when it is closed is because it has line symmetry. When an object is folded along its line of symmetry the two halves match. A line of symmetry divides an object into two mirror images. One side is a reflection of the other.

Take a look at the picture below.

The dotted line shows the line of symmetry. A line of symmetry can be a vertical line, a horizontal line, or a diagonal line.

How can you find the lines of symmetry for an object?
Fold the figure in half. If the two sides match, then the fold is a line of symmetry.

An object can have more than one line of symmetry. For example you can fold a rectangle in half horizontally, vertically, or diagonally, and each half matches the other. A rectangle has four lines of symmetry.


If you turned a rectangle upside down, would it look the same? Yes! This is called turn symmetry. If an object looks the same when it is turned, it has turn symmetry.

These objects have turn symmetry.

 

How can you find if an object has turn symmetry? Turn the figure. If it looks the same as it did before, it has turn symmetry.

An object has line symmetry if you can fold the object, and one half looks exactly like the other. An object has turn symmetry if you can turn it part way around and it still looks the same. An object can have either line or turn symmetry, or both line and turn symmetry, or no symmetry at all.

 

EXERCISES
Use pencil and paper to solve the following:

Use the figures below to answer the following questions.

1. Which figure(s) have one line of symmetry?
2. Which figure(s) have more than one lines of symmetry?
3. Which figure(s) have turn symmetry?
4. Is it possible to have a figure with turn symmetry but not line symmetry?
5. Find 3 figures in real life that have lines of symmetry.


REVIEW
Use pencil and paper to solve the following:
Write each fraction as a decimal to the nearest hundredth. Use a calculator if necessary.
1. 56/56
2. 12/48
3. 3/96
4. 10/100
How many decimal places is in each product below.
5. 9.23 x 5
6. 78.023 x 34.23
7. 1,031 x 0.02
8. 9.912 x 9.0099
Write the missing number.
9. 78 km = ____ m
10. 9 cm = ___ m
11. 23 mm = ____ cm
12. 42 cm = ____km
Divide using Mental Math.
13. 63,000 ÷ 10,000
14. 89 ÷ 1,000
15. 2 ÷ 10,000
16. 0.92 ÷ 10
17. 45 ÷ 100
 
   
   
   
   

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