GRADE 8 Pre-technical COMMUNICATION – PLAIN SCALE DRAWING Notes

PLAIN SCALE DRAWING

Subject: Pre-technical — Topic: COMMUNICATION
Level: Age 13 (Kenya) — Simple notes and examples for making drawings to scale.

What is a plain scale drawing?

A plain scale drawing is a simple drawing of an object or place (for example a classroom, plot of land or a piece of furniture) shown smaller or larger than the real thing, but keeping the correct shape and proportions. The drawing uses a scale such as 1:50 or 1:100 to convert real measurements to paper measurements.

Key words

• Scale: The ratio between a length on the drawing and the real length. Example: 1:50 (one on paper equals fifty in real life).
• Reduction: When the object on paper is smaller than the real object (e.g., 1:100).
• Enlargement: When the object on paper is larger (e.g., 2:1).
• Representative Fraction (R.F.): Another name for the scale written as a fraction: 1/50, 1/100.

Common simple scales

For drawings of rooms or small plots, use scales like 1:50, 1:100 or 1:25. For example:

• 1:50 — good for classroom plans (1 cm on paper = 50 cm in real life).
• 1:100 — good for a small compound or field (1 cm on paper = 100 cm = 1 m).
• 1:25 — shows more detail (1 cm on paper = 25 cm real).

Tools you need

Pencil, eraser, ruler, measuring tape (for real lengths), paper and a sharpener. A scale bar or scale rule is helpful but not necessary.

How to make a plain scale drawing — step by step

1. Measure the real object in metres or centimetres (for example measure your classroom).
2. Choose a scale that fits your paper (e.g., 1:50 or 1:100).
3. Convert the real measurement to the drawing length using the scale: drawing length = real length ÷ scale factor (when real length in same units as scale).
4. Use a ruler to mark the lengths on paper and draw lines carefully.
5. Label each dimension (e.g., 6 m → 12 cm on drawing) and show the scale (e.g., Scale 1:50).
6. Draw a small scale bar on the drawing (shows how long 1 m or 5 m is on the paper).

Worked example (Kenya classroom)

Real classroom size: 6.0 m by 5.0 m. Choose scale 1:50.

Convert metres to centimetres first: 6.0 m = 600 cm, 5.0 m = 500 cm.
At scale 1:50, drawing length = real cm ÷ 50:

• Length on paper = 600 ÷ 50 = 12 cm
• Width on paper = 500 ÷ 50 = 10 cm

So draw a rectangle 12 cm by 10 cm on your paper. Label: "Classroom — 6.0 m × 5.0 m, Scale 1:50".

Practice questions

1. Draw your bedroom plan. Real size 4.0 m × 3.5 m. Use scale 1:50. What are the paper lengths?
2. A small shop is 8 m long and 4 m wide. If you use scale 1:100, what are the lengths on paper (in cm)?
3. Convert a drawing length of 15 cm at scale 1:75 to the real length in metres.

Answers

• Bedroom: 4.0 m = 400 cm → 400 ÷ 50 = 8.0 cm; 3.5 m = 350 cm → 350 ÷ 50 = 7.0 cm.
• Shop: 8 m = 800 cm → 800 ÷ 100 = 8.0 cm; 4 m = 400 cm → 400 ÷ 100 = 4.0 cm.
• Real length = drawing × scale = 15 cm × 75 = 1125 cm = 11.25 m.

Tips for neat plain scale drawings

• Always write the scale clearly on the drawing (e.g., Scale 1:50).
• Label the real measurements (e.g., 6.0 m) and the drawing measurements (e.g., 12 cm).
• Use light pencil lines first. Darken the final lines when correct.
• Include a north arrow if the drawing shows direction (useful for plots).

Try drawing a small plan of your school field using scale 1:200. Measure and convert — this helps when you need to communicate sizes and space in real life.