Good Learning Co.
SavannahYear 8
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ScienceWorking scientifically25 min★★ difficulty

Measuring accurately and judging reliability

Numbers only mean something if you trust how they were collected. Reliability is about whether you'd get the same answer again.

Part of your national curriculum
  • Working scientifically: Make and record observations and measurements using a range of methods, and evaluate the reliability of methods

Lesson overview

What you'll learn in this lesson

Make and record observations and measurements using a range of methods, and evaluate the reliability of methods

Key learning points

  • • Choosing the right instrument
  • • Repeating readings
  • • Judging reliability

This lesson at a glance

  • 25 minutes
  • 14 parts to scroll through
  • 3 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

recordobservationsmeasurementsmethodsreliability

Scroll down — the lesson carries on below

Part 1 of 14 · Discover7%
1

Watch & discover

Part 1 of 14

Watch first

Measuring accurately and judging reliability

An English teaching video on this topic from Smart Learning Ltd. Watch it, then scroll down for the lesson.

In a nutshell

Make and record observations and measurements using a range of methods, and evaluate the reliability of methods

2

Learning cycle

Part 2 of 14

Learning cycle 1 of 2

Part 1 · Choosing the right instrument

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 14

Learn

Choosing the right instrument

A measuring cylinder gives finer volume readings than a beaker; a data logger with a thermometer probe can record temperature every second, more precisely than a person reading a thermometer by eye. Choosing sensitive, appropriate equipment reduces error.

4

Explore the idea

Part 4 of 14

Learn

Repeating readings

Taking repeat measurements and calculating a mean reduces the effect of random errors — small, unpredictable variations. If one reading is very different from the others (an anomaly), it can be identified and excluded before averaging.

5

Quick check

Part 5 of 14

Quick check

What does repeating an experiment and averaging help reduce?

6

Reset break

Part 6 of 14

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
7

Quick check

Part 7 of 14

Quick check

An anomalous result is one that is:

8

Learning cycle

Part 8 of 14

Learning cycle 2 of 2

Part 2 · Judging reliability

A short piece of teaching, then a check to make sure it has landed.

9

Explore the idea

Part 9 of 14

Learn

Judging reliability

A method is reliable if repeating it gives similar results each time. Close, consistent repeat readings suggest high reliability; widely scattered readings suggest the method needs improving, perhaps with better control of variables or more precise equipment.

10

Quick check

Part 10 of 14

Quick check

A method is reliable if:

11

Challenge round

Part 11 of 14

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

12

Challenge round

Part 12 of 14

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

A measuring cylinder gives finer volume readings than a beaker; a data logger with a thermometer probe can ____ temperature every second, more precisely than a person reading a thermometer by eye.

Taking repeat ____ and calculating a mean reduces the effect of random errors — small, unpredictable variations.

Close, consistent repeat readings suggest high ____; widely scattered readings suggest the method needs improving, perhaps with better control of variables or more precise equipment.

13

Mastery quiz

Part 13 of 14

Marked quiz

End of lesson quiz: Measuring accurately and judging reliability

3 questions, marked with the reasoning shown. No timer.

  1. 1. What does repeating an experiment and averaging help reduce?

  2. 2. An anomalous result is one that is:

  3. 3. A method is reliable if:

14

Lesson round-up

Part 14 of 14

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 14 · Watch & discover

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    Make and record observations and measurements using a range of methods, and evaluate the reliability of methods

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