Grade 7 Pre-technical TOOLS AND PRODUCTION – MEASURING AND MARKING OUT TOOLS Notes

MEASURING AND MARKING OUT TOOLS

Subject: Pre-technical — Topic: Tools and Production
Target age: 12 years (Kenya)

What are these tools?

Measuring and marking out tools help us to find and show the exact size, shape and position of parts before we cut or join them. In Kenya we use the metric system: millimetres (mm), centimetres (cm) and metres (m).

Common measuring tools

• Ruler / Steel rule — usually 30 cm. Used for short straight measurements and drawing straight lines. ✏️📏
• Tape measure — 2 m, 5 m or more. Good for measuring tables, doors and rooms. (Used a lot in building and tailoring.)
• Protractor — measures angles in degrees (0°–180°). Useful for marking angles on materials.
• Try square — checks and marks right angles (90°). Used in woodworking and metalwork.
• Calipers (simple vernier/digital) — measure small distances and thickness accurately (to mm or 0.1 mm).

Common marking out tools

• Pencil — soft pencil (HB) for general marking.
• Scriber — makes thin scratch lines on metal or wood for exact cutting lines.
• Marking gauge — marks parallel lines from the edge of wood (useful in joinery).
• Centre punch — makes a small dent on metal so drills do not slip.

Simple visuals

How to measure and mark correctly (simple steps)

1. Pick the right tool: ruler for small jobs, tape measure for long lengths.
2. Place the tool flat and steady on the object.
3. Read the measurement at eye level to avoid mistakes (parallax error).
4. Make a small light mark with a pencil or scribe where needed.
5. Check your measurement again before cutting.

Safety and care

• Keep metal tools dry to stop rust. Wipe and oil lightly if needed.
• Store sharp tools (scribers, punches) in a box or with covers to avoid injuries.
• When using a centre punch, wear safety glasses — small metal chips can fly.
• Do not use a measuring tape as a ruler for writing — it can snap back and hurt you.

Short classroom activities (5–15 minutes)

1. Measure your desk length and width in cm. Record the numbers.
2. Use a try square to check if a book corner is a right angle (90°).
3. Mark the centre of a 20 cm wood strip: measure 20 ÷ 2 = 10 cm and mark at 10 cm.
4. Quiz: Which tool would you use to measure the length of a classroom wall? (Answer: tape measure)

Quick tips for Kenyan students

• Remember metric units: 100 cm = 1 m; 10 mm = 1 cm.
• In tailoring you may use a flexible cloth tape; in building use a long steel tape.
• Always double-check important measurements. Measure twice, cut once.