Basic 9 · Career Technology · Measuring and Marking Out
Measuring and Marking Out Tools
In this topic you will discuss the tools and equipment used for measuring and marking out, classify them and use them accurately.
By the end of these notes you should be able to:
- Identify tools for measuring and marking out
- Classify measuring and marking out tools
- Use measuring tools accurately
What you already know
- Units of measurement
- Workshop safety
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
Lesson 1
- Strand
- Tools
- Sub-strand
- Measuring and Marking Out
- Indicator
- B9.3.1.1.1 – Discuss tools and equipment used for measuring and marking out
Introduction
Skilled workers follow one golden rule: measure twice, cut once.
1. Why Accuracy Matters
Measuring finds the size of something, and marking out transfers that size onto a material. Accurate work prevents waste. A carpenter who cuts a door 2 cm short has wasted a costly piece of timber. A dressmaker who measures wrongly may spoil a client's cloth. A nurse must measure medicine exactly. Good measuring saves money, builds trust and leads to better products.
2. Measuring Tools
| Tool | Use | Field |
|---|---|---|
| steel rule | short, exact lengths | metalwork, woodwork |
| tape measure | long lengths | building, sewing |
| vernier calliper | small lengths with precision | engineering |
| micrometer | very small thicknesses | engineering |
| spirit level | checking if level | building |
| measuring jug | liquid volume | cooking |
| kitchen scale | mass | cooking |
| thermometer | temperature | cooking, health |
3. Marking-Out Tools
| Tool | Use | Field |
|---|---|---|
| pencil | marking lines | woodwork |
| marking knife | fine lines in wood | woodwork |
| try square | right angles | woodwork, metalwork |
| marking gauge | lines parallel to an edge | woodwork |
| scriber | marks on metal | metalwork |
| centre punch | marks before drilling | metalwork |
| dividers | circles and arcs | metalwork |
| tailor's chalk | marks on cloth | sewing |
| tracing wheel | pattern marks on cloth | sewing |
| chalk line | long straight lines | building |
4. Reading a Measurement
Metric units are used in Ghana for most measuring. 10 mm = 1 cm, 100 cm = 1 m and 1,000 mm = 1 m. Look straight down at the rule, not from an angle, in order to avoid error. Measure from a clean, flat edge, and be careful if the end of a rule is worn. Write down measurements at once, and always include units. Some trades still use inches and feet, so it is useful to know that 1 inch is about 2.5 cm.
5. Choosing the Right Tool
Select the tool to suit the accuracy needed. A tape measure suits a room, but it is not suitable for a thin metal rod. A steel rule measures to about 0.5 mm, while a vernier calliper measures to about 0.1 mm or better. Using the correct tool for the task saves time and improves quality.
New words
- marking out
- Transferring measurements to a material.
- accuracy
- How close a measurement is to the true value.
- try square
- A tool for checking right angles.
- vernier calliper
- A tool for measuring small lengths.
Summary
- Accurate measuring reduces waste and improves quality.
- Measuring tools find size, and marking-out tools transfer it.
- Choose the correct tool for the accuracy needed.
Class activity: Tool Identification
- Examine tools from the workshop.
- Name each tool and its use.
- Record them in a table.
You need: Tape measure, Steel rule, Combination square
Exercises
Answer in your exercise book first, then check your answers.
1. A try square checks…
- A. right angles
- B. temperature
- C. weight
- D. colour
Show answer
Answer: right anglesAngle.2. A scriber is used to mark…
- A. metal
- B. cloth
- C. water
- D. food
Show answer
Answer: metalMetalwork.3. Measure twice, cut once.
- A. True
- B. False
Show answer
Answer: TrueRule.4. 100 cm equals ______ m.
Show answer
Answer: 1Units.5. Name three measuring tools.
Show answer
Answer: Steel rule, tape measure and vernier calliper.Any three.6. Why is accuracy important in business?
Show answer
Answer: It prevents waste, saves money and earns customers' trust.Value.
Lesson 2
- Strand
- Equipment & Processes
- Sub-strand
- Measuring and Marking Out
- Indicator
- B9.3.1.1.1 – Discuss tools and equipment used for measuring and marking out
Introduction
Tools can be sorted by what they measure and by the trade that uses them. Knowing these groups helps you to choose well.
1. Classifying Tools
| Class | Examples |
|---|---|
| direct measuring | steel rule, tape, measuring jug |
| indirect measuring | callipers, dividers |
| precision | vernier calliper, micrometer |
| checking | try square, spirit level |
| marking | scriber, chalk, gauge |
Direct measuring tools give a reading straight from the tool. Indirect tools pick up a distance, which is then read on a rule. Precision tools measure very small differences. Checking tools test whether something is correct, for example square or level, and they do not give a number.
2. Using a Try Square
- Hold the stock firmly against a straight edge of the wood.
- Slide the blade to your mark.
- Draw a line along the blade with a sharp pencil or marking knife.
- Check the corner by placing the square inside it.
- Look for light between the square and the wood.
3. Using a Spirit Level
A spirit level contains a tube of liquid with an air bubble. When the bubble sits between the two lines, the surface is level. Masons use it when building walls and laying tiles. A wall that is not straight may be weak and would look bad. Plumb lines, which are weights on strings, show true vertical.
4. Measuring in Sewing and Cooking
| Trade | Example of measuring |
|---|---|
| dressmaking | bust, waist and hips with a tape |
| catering | flour by mass, water by volume |
| hairdressing | correct amounts of hair products |
| electrical | voltage with a multimeter |
| agriculture | spacing between crops |
Scaling a recipe
A recipe for 4 people needs 300 g of rice. How much rice is needed for 10 people?
- For 1 person: 300 ÷ 4 = 75 g.
- For 10 people: 75 × 10.
Answer: 750 g
5. Caring for Measuring Tools
Treat measuring tools gently. Do not drop them, and keep them clean and dry. Oil steel tools lightly to prevent rust. Do not use a steel rule as a screwdriver. Check tapes for stretched or worn ends. A damaged tool gives false readings, and this can spoil your work. Store precision tools in their cases. Tools should be checked regularly against a known standard, a process called calibration.
New words
- precision
- The fineness of a measurement.
- calibration
- Checking a tool against a standard.
- plumb line
- A string and weight showing vertical.
- spirit level
- A tool that shows if a surface is level.
Summary
- Tools can be classified as direct, indirect, precision, checking and marking.
- Each tool has a correct method of use.
- Care and calibration keep tools accurate.
Class activity: Measuring Challenge
- Use a rule, tape and try square to measure five objects.
- Record your results with units.
- Compare with your partner's.
You need: Tape measure, Steel rule, Combination square
Exercises
Answer in your exercise book first, then check your answers.
1. A spirit level shows whether something is…
- A. level
- B. hot
- C. wet
- D. heavy
Show answer
Answer: levelBubble.2. Which is a precision tool?
- A. micrometer
- B. chalk
- C. hammer
- D. broom
Show answer
Answer: micrometerFine.3. A damaged tool can give false readings.
- A. True
- B. False
Show answer
Answer: TrueCare.4. Checking a tool against a standard is ______.
Show answer
Answer: calibrationAccuracy.5. Describe how to use a try square.
Show answer
Answer: Hold the stock against the edge, slide the blade to the mark and draw the line.Steps.6. A recipe for 6 needs 450 g of flour. How much for 8?
Show answer
Answer: 600 g75 g each.
Homework
- Measure ten objects at home using the correct tools and units.