G1 Measurement and Multimeter Skills
Key idea: Learn how to measure common quantities, determine average speed and use a multimeter safely at G1 Science level.
Continue where you stopped
The core idea
Measure with purpose, not by guesswork
A good measurement is more than a number. You must choose a suitable instrument, use it correctly and record a value that another person can understand.
What you will be able to do
- measure length, mass, temperature, time interval, liquid or solid volume, and force;
- determine the average speed of an object;
- measure current, voltage and resistance with a multimeter.
1. Choose the right instrument
Start with the quantity you need, not with the apparatus on the bench. Then check that the instrument has a suitable range and scale. A 30 cm ruler cannot measure a 2 m table in one reading, while a large measuring jug is a poor choice for a few drops of liquid.
| Quantity | Suitable instrument | How to use it well | Common unit |
|---|---|---|---|
| Length | Ruler or measuring tape | Place zero at one end; read straight above the mark. | mm, cm or m |
| Mass | Electronic balance | Zero the balance first; keep the object dry and centred. | g or kg |
| Temperature | Thermometer or temperature probe | Keep the sensing part in the substance and wait for a steady reading. | °C |
| Time interval | Digital stopwatch | Use clear start and stop events; repeat when reaction time can vary. | s or min |
| Liquid volume | Measuring cylinder | Place it upright; for water, read the bottom of the meniscus at eye level. | cm³ or mL |
| Regular solid volume | Ruler, then calculate | Measure the needed dimensions, such as length × width × height. | cm³ |
| Irregular solid volume | Measuring cylinder and water | Find final water volume − initial water volume. | cm³ |
| Force or weight | Newton meter | Check zero, select a suitable range and pull in line with the scale. | N |
2. Take a trustworthy reading
Good technique makes your reading more dependable. Follow the same short routine whenever you measure.
- Check.Is the instrument undamaged, set to zero and able to cover the expected value?
- Position.Place the instrument correctly. Read a scale at eye level to avoid a viewing error.
- Read.Record all digits shown by a digital instrument, or read to the nearest marked division on a simple scale.
- Record.Write the value and unit immediately. A bare number such as “12” is incomplete.
- Repeat.Repeat readings that may vary. Similar repeats increase confidence; a very different result should be checked, not silently deleted.
Check your understanding
A student reads a measuring cylinder while looking down from above. How should the method be improved?
Show the guided answer
Place the cylinder upright on a level surface and bring your eye level with the liquid surface. For water, read the bottom of the meniscus. This reduces the viewing error caused by looking from above.
3. Determine average speed
Average speed describes how much distance is covered per unit time over the whole measured journey.
average speed=total distancetotal time
If distance is measured in metres and time in seconds, average speed is measured in metres per second, written m/s.
A simple practical method
- Mark a start and finish line and measure the distance between them.
- Release the object in the same way for each trial. Do not give it an extra push unless that is part of the method.
- Start and stop the timer as the same reference point on the object crosses each line.
- Repeat the timing. If the distance stays fixed, find the average time, then calculate the average speed.
Try it with support
A battery-powered car covers 5.4 m in 9.0 s. Determine its average speed.
- Write average speed = total distance ÷ total time.
- Substitute 5.4 m and 9.0 s.
- Give the answer in m/s.
Check your answer
Average speed = 5.4 ÷ 9.0 = 0.60 m/s.
4. Use a multimeter safely
A multimeter can measure several electrical quantities, but you must change both its setting and sometimes its connection. Use only the low-voltage circuits provided by your teacher.
Current
Select current mode and connect the meter in series, so the circuit current passes through it. Begin with a range that is high enough for the expected current.
Voltage
Select voltage mode and connect the meter in parallel across the component or source. The meter compares two points.
Resistance
Switch off and disconnect the external power first. Select resistance mode and place the probes across the isolated component. The meter uses its own small internal source.
Check your understanding
A student wants to measure the resistance of a resistor that is still connected to a switched-on circuit. What should the student change?
Show the guided answer
Switch off and disconnect the external power, isolate the resistor, select resistance mode and then place the probes across the resistor.
5. Record and check results
A results table should make sense without a spoken explanation. Put the quantity and unit in each heading, keep the recording style consistent and include every repeat.
| Trial | Distance / m | Time / s | Average speed / m/s |
|---|---|---|---|
| 1 | 2.00 | 3.9 | 0.51 |
| 2 | 2.00 | 4.1 | 0.49 |
| 3 | 2.00 | 4.0 | 0.50 |
The three results are close, so they support an average speed of about 0.50 m/s. If one result were very different, repeat that trial and look for a reason such as a late stopwatch start.
For a practical question
Name the instrument, say how it is positioned or connected, state what you record and include the unit. If readings can vary, say that you repeat them and calculate an average. Specific steps earn more credit than “measure carefully”.
6. Worked Examples
Modelled example 1
Find the volume of an irregular stone
Problem
Water in a measuring cylinder rises from 42 cm³ to 57 cm³ when a stone is fully submerged. Determine the stone’s volume.
Study the worked solution
Choose the two readings
Method
Use the water level before and after the stone is submerged.
Reason
The stone’s volume equals the volume of water it displaces, which is the rise in the reading.
Working
initial volume = 42 cm³; final volume = 57 cm³
Find the change
Reason
Subtracting removes the water that was already in the cylinder.
Working
stone volume = 57 cm³ − 42 cm³ = 15 cm³State the measured volume
Working
The stone’s volume is 15 cm³.
Guided practice 2
Determine a trolley’s average speed
Problem
A trolley travels 3.6 m in 4.5 s. Determine its average speed.
Write the relationship, substitution and answer
Hints
Hint 1: choose the relationship
Average speed uses the total measured distance and total measured time.
Hint 2: substitute with units
Divide 3.6 m by 4.5 s.
View solution step by step
Select the measured quantities
Method
Use average speed = total distance ÷ total time.Reason
The question describes the complete measured journey rather than the speed at one instant.
Working
average speed = 3.6 m ÷ 4.5 sCalculate and record the unit
Reason
Metres divided by seconds gives metres per second.Working
average speed = 0.80 m/s
Common misconception 3
Correct an unsafe current measurement
Learner plan
“I will select current mode and place the multimeter probes directly across the cell.” Identify the danger and replace the plan with a safe connection.
Explain the first error and the correction
View solution step by step
Locate the first unsafe decision
Method
Reject the across-the-cell connection while the meter is in current mode.
Reason
Current mode has very low resistance, so this connection can produce a very large current and damage the meter or source.
Working
Unsafe: current mode connected directly across the supply.
Rebuild the circuit safely
Method
Switch off, break the intended current path and insert the meter in series.
Reason
The current being measured must pass through the meter without creating a separate low-resistance path.
Working
Safe: begin on a suitable high range, connect in series, ask for a check, then switch on.
Examiner practice 4
Plan a reliable average-speed measurement
Examination question
Describe how to determine the average speed of a toy car over a marked track using a measuring tape and digital stopwatch. Include one way to improve confidence in the result. [4 marks]
Write a four-mark practical method
View solution step by step
Measure a defined distance
1 markMethod
Mark start and finish lines and measure the distance between them with the tape.
Reason
A defined distance is needed for the average-speed relationship.
Working
Record the distance in metres.Measure the matching time
1 markMethod
Time the same reference point on the car crossing the two lines.
Reason
Clear start and stop events make trials comparable.Working
Record the journey time in seconds.Repeat and calculate
2 marksMethod
Repeat with the same release, find a mean time and divide distance by mean time.
Reason
Repeats reveal timing variation and reduce the influence of one unusually early or late response.
Working
average speed = measured distance ÷ mean time, in m/s
Self-mark with the mark scheme
Compare your response with each mark point. Select a point only when your response contains that evidence.
Self-mark the distance, timing, repeat and calculation points separately.
Challenge 5
Change from measuring current to resistance
Problem
A multimeter is connected in series in a switched-on circuit to measure current. The learner must now measure the resistance of one resistor. Describe every change needed before taking the new reading.
Reconfigure the equipment safely
Hints
Hint 1: start with the energy source
Resistance mode must not be used on the still-powered component.
Hint 2: change both setting and connection
Think about the supply, the component, the lead sockets, the mode and where the probes go.
View solution step by step
Make the component safe to test
Method
Switch off and disconnect the external supply, then isolate the resistor from the circuit.
Reason
The meter supplies its own small test signal in resistance mode, so another live source would make the reading invalid and may damage the meter.
Working
Power off → supply disconnected → resistor isolated.
Change the meter and connection
Method
Move the leads if the meter requires it, select resistance mode and connect the probes across the resistor.
Reason
Resistance is measured across the isolated component rather than by keeping the current-mode series connection.
Working
Correct sockets → resistance mode → suitable range → probes across resistor.
7. Practise this
Check your three opening answers
- Use a measuring cylinder for 36 cm³ of water.
- Average speed = 4.8 m ÷ 6.0 s = 0.80 m/s.
- Connect a voltmeter in parallel across the component.
1. Select and explain
Choose an instrument for each measurement: the mass of an apple, the temperature of water, the weight of a bag and 25 cm³ of liquid. Give a suitable unit for each.
Check your answer
Use an electronic balance with g or kg; a thermometer or temperature probe with °C; a newton meter with N; and a measuring cylinder with cm³ or mL.
2. Calculate and check
A robot travels 7.5 m, stops for 5.0 s and then travels another 2.5 m. The whole journey takes 25.0 s. Determine its average speed.
Need a hint?
Add both distances. Use the whole journey time, including the stop.
Check your answer
Total distance = 10.0 m. Average speed = 10.0 m ÷ 25.0 s = 0.40 m/s.
3. Correct the circuit plan
A student says, “I can measure current by placing a multimeter in current mode across the cell.” Explain the mistake and give the correct connection.
Check your answer
Connecting current mode directly across a cell can create a very large current and damage the meter. Switch off first, then rebuild the circuit so the multimeter is in series with the component whose current is being measured.
Continue with the next resource in this course.
Course and syllabus information
- Course
- SEC G1 Science
- Edition
- SEC G1 Science 2027