By Zani Alam Once I was asked by

By Zani Alam

Once I was asked by my teacher to draw a picture of a CD. I grabbed a ruler, measured out all dimensions (width and height) carefully. Then I drew the CD based on those dimensions. This is was an easy task. Then my teacher asked me to draw my bedroom. I thought this would be difficult but once the teacher explained to me about scale drawing and gave some examples, it became an easy task for me. I just had to give my self a chance to listen to the explanation and to investigate more about scale drawing.

Meaning of the word scale in everyday life The numbers on a measuring instrument Fish A weighing machine Scale 2 - The ratio or proportion of size on a map or diagram Rust and flaky chemicals on metal are called scales This type of scale we are going to look at today

4 -Rust and flaky chemicals on metals are called scales 2 -Fish have scales Scale 5 - The numbers on a measuring instrument used to make reading 1 -A weighing machine 3 - The ratio or proportion of size on a map or diagram This is the focus for our lesson.

Is a proportional 2 dimensional drawing of an object. A Scale drawing Scale Gives the ratio that compares the measurement of the drawing with the actual measurements. Can be shown as fraction: 1/100 or ratio 1: 100

Is a proportional 2 dimensional drawing of an object. A Scale drawing Gives the ratio that compares the measurement of the drawing with the actual measurements. The number of times the original has been reduced or enlarged e A scale factor A scale model Scale Can be shown as fraction: 1/100 or ratio 1: 100 Is a proportional 3 dimensional model of an object.

In scale drawing there are two types of problems: The first type involves calculating the real sizes of objects from the drawing. The second type involves making a scale drawing of an object.

1 - Calculating the real sizes of objects from drawing A- The scale on drawing is 1: 100. What is the real distance between two points that are 5 cm apart on the drawing. Real distance: 5 x 100 = 500 cm =5 m 1: 100 1 cm on the drawing Means 1 cm on the drawing represents 100 cm in real life

1 cm =10 mm

Connections with the real world Scale drawings are everywhere! 1. 5 m 15 cm Scale drawing Pool design House design

Why scale drawings? If it's just a small object that you want to represent on paper, full size drawings are great. But, if you want to draw, say, a room with furniture, you're going to need a huge piece of paper to sketch it. As you know, we don't do this. We do "scale drawings" - we make our sketches smaller so they can fit on one sheet of paper.

Why do we need to use scale to draw objects or house plans etc. ? We can't fit the true measurements onto a piece of paper.

Plans and maps use a scale. The scale is written as a ratio. The first number in a ratio represents the drawing, while the second number represents the real object. Example: Drawing length: Actual length 1: 100 Drawing Actual length(Real object) to The ratio 1 cm: 100 cm means that for every 1 cm on the scale drawing the length will be 100 cm in real life

An objet and its scale drawing are similar figures. Two objects are SIMILAR means that they are identical in shape, but not in size.

• This house drawing measures 10 cm in length. • The scale used here is 1 cm: 250 cm (2. 5 m) • This means that every centimetre on the drawing actually represents 2. 5 metres length in real life. If the house (drawing) measures 10 cm in length what is the true length of the house? 10 x 250=2500 cm =25 m is the true length of the house.

Station 2 Station 1 Scale drawing stations Station 4 Station 3

Soccer is played on a rectangular field (46 to 91 meters) in width (91 to 119 meters) in length

Station 1 Terry used a scale of 1 cm representing 1600 cm (16 m) when he drew this scale drawing of a soccer field. (1: 1600) What are the dimensions of the soccer field? The length of the soccer field is already measured for you. Answer the following questions: The length of the field in the scale drawing (on the diagram) is ______ cm Each centimetre means ______ in real life. Real length of the soccer field= The width of the field on the diagram is ____ cm Real width of the soccer field is _________

answers Station 1 Terry used a scale of 1 cm representing 1600 cm (16 m) when he drew this scale drawing of a soccer field. (1: 1600) What are the dimensions of the soccer field? The length of the soccer field is already measured for you. You need to use your ruler to measure the width. The length of the field in the scale drawing (on the diagram) is 6 cm. Each centimetre means : 1600 cm in real life or 16 m Real length of the soccer field= 6 x 1600= 9600 cm= 96 m The width of the field on the diagram is : 3 cm Real width of the soccer field is : 3 x 1600=4800 cm = 48 m

Calculate the real size of each item: Station 2 A) Scale: 1 cm represents 200 cm (1: 200) Use your ruler to measure the length of the flag. Answer: 1 - The length of the flag on the drawing is: ______ 2 - Each centimetre on the drawing represents 200 cm (2 m) in real life. 3 - Real length =_______ B) Scale: 1 cm represents 15 cm (1 cm: 15 cm) Answer: 1 -The length of the bike on the drawing is: _______ 2 - The real length of the bike is: _______

Station 3 1 Vocabulary with scale drawing Fill in the missing words using the following: Real life - Drawing-Actual -Ratio-Big-Scale 1 A scale drawing is a _____ that compares the measurement of the drawing with the _____ measurements. 2 When we want to draw ______ objects we use ______ drawing. 3 A scale of 1 cm: 100 m means every cm on the _____ represents 100 m in ________. Pool design

Station 4 What is the length of the bed on the diagram: _____ Real length: _______ What is the width of the bed on the diagram: ______ Real width: ________ Scale: 1: 20