ACTIVITY: Geometry [LO 1.8, LO 3.4]

1. Let us begin with a class discussion. What, do you think, is GEOMETRY all about?

2. Did you know?

Geometry is derived from two Greek words? Decipher the code and find out what the two words are.

1.

a) 72 ÷ 8

b) 7 x 6

c) 9 x 4

d) 9 x 6

e) 144 ÷ 12

________________

(geo)

2.

a) 12 x 8

b) 36 ÷ 4

c) 29 + 13

d) 56 − 18

e) 11 x 4

f) 12 x 3

_________________

(metry)

Figure 7

3. Did you know?

More than 5 000 years ago, the Ancient Egyptians in the Nile Valley applies geometrical rules to build their pyramids. The Babylonians also used geometry to build their temples and to develop their irrigation systems. The famous Greek geometrician, Euclid, lived 300 B.C. According to him, the foundations of geometry are points, lines and planes.

4. BRAIN TEASER!

a) What is the shortest possible line?___________________________________

b) What do we get when we join two lines together so that they bisect each other? ______________________________________________________________

c) What do we get when we add more lines to b?_________________________

5. IMPORTANT FACTS to KNOW

POINT: A point only has a position and no size.

We indicate it with a small dot ( Ÿ ).

LINE: When we have two points, we can draw a line through them.

A line only has length and neither breadth nor height

A straight line has no beginning or end.

Figure 8

LINE SEGMENT: A line segment is part of a line. It has a starting point and an end point.

Figure 9

RAY: A ray has a beginning point. It continues indefinitely in the same direction and doesn’t have an end point. (Think of the rays of the sun.)

Figure 10

PLANE: A plane has length and breadth (two-dimensional), but not height. You can perceive it as a “flat” space, e.g. a rectangle.

Figure 11

6. BRAIN-TEASER!

a) What do we call this line? . . . . . . . . . . . . . . . . .

It is used when we are constructing a figure.

_____________________________________________________________________

b) What do we call this line? _____________________

It is usually dark and is used for the final lines of a drawing.

_____________________________________________________________________

c) This line is used for hidden or invisible lines. _ _ _ _ _ _ _

(it is not a dotted line)

_____________________________________________________________________

7.1 Do you still remember?

§ Can you fill in the missing answers?

a) Kinds of lines: Lines can be:

Figure 12

ii)

Figure 13

:

iii)

Figure 14

b) Lines that are equidistant from each other and never meet are called

_________________________________________________________ lines.

We use the symbol _________________to show the lines “are parallel to each other.”

c) Two lines are ______________________________ to each other when they bisect each other, forming a 90° angle.

We call this angle a _______________________________________________ angle.

We use the symbol ___________________ to indicate “is perpendicular to”.

7.2 Design a wall hanging by making use of horizontal and vertical lines only. Colour it in neatly.

7.3 Can you explain to a friend how one draws a perpendicular line?

7.4 Can you explain how we draw parallel lines?

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

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_____________________________________________________________________

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8. LET US TEST YOUR KNOWLEDGE!

Figure 15

How many line segments are in the sketch?__________________________________

Please name them: _____________________________________________________

_____________________________________________________________________

Measure the length of each line segment: ___________________________________

_____________________________________________________________________

Figure 16

Name the four rays in the sketch.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

c) Draw line EF.

Figure 17

d) Draw line segment GH 32 mm long.

Figure 18

e) Draw ray MN.

Figure 19

f) Draw KL // OP.

Figure 20

g) Draw VW XY.

Figure 21