Science experiments: listening answers and explanations
Two trainee teachers, Sue and Mike, need two science experiments to do with a class of eight-year-olds. They go through five experiments from a library book, noting the equipment and purpose of each, then reject them one by one for different reasons.
Two passes through the same five experiments. Questions 21-26 come from the first pass, where each experiment is described in order. After 'Shall we go through all of those again', Questions 27-30 come from the second pass, where they find a problem with each one, again in order.
Answer key and self-check
Type what you wrote and hit mark. Hide the key first if you haven't done the part yet. Every question number jumps to its explanation.
Q
Your answer
Answer
Questions 21-26 · Table completion (NO MORE THAN THREE WORDS AND/OR A NUMBER)
Table completion (NO MORE THAN THREE WORDS AND/OR A NUMBER)
Questions 21-26
How to attack this block: Each experiment is described as equipment first, then purpose, matching the table. The equipment gaps need nouns, sometimes with a number. Watch for items that are suggested and dropped, and for things added as an afterthought.
Question 21
Answer: 20 balloonsWhen they start on the first experiment, 'make your own hovercraft'
Also accepted: twenty balloons
What do you need, apart from a table, for the hovercraft experiment?
Mind you, you only need 20 balloons and a table. You don't need any special engines or anything like that.
Question says → You hear
Equipment: ... and a tableyou only need 20 balloons and a table
Why: The table is printed, so the gap is 20 balloons. Include the number: it's part of what you need.
The trap: 'Special engines' are mentioned straight after, but as something you don't need.
Question 22
Answer: units of measurementExperiment two, 'unusual measures of lengths'
Also accepted: units / measurements / measurement units
What does the paper clip experiment show we need?
It's supposed to demonstrate the importance of having fixed units of measurement.
Question says → You hear
to show why we need standardthe importance of having fixed units of measurement
Why: 'Standard' in the table is 'fixed' in the talk, so the gap is units of measurement.
The trap: 'Lengths' is used a lot here, and some people write 'lengths'. The point is not length itself but having fixed units to measure it.
Question 23
Answer: rock saltWhen they move on to number three
Also accepted: salt
Apart from a jar of water, what does Experiment 3 need?
you need rock salt or copper sulfate. Oh, I'm not sure about that. Well, just put down the rock salt then.
Question says → You hear
Equipment: ... and a jar of waterjust put down the rock salt then … you only need a jar of water
Why: Copper sulphate is dropped, and they agree to 'just put down the rock salt'. The jar of water is printed.
The trap: Copper sulphate is offered as an alternative, but they don't write it down. Writing it, or both, loses the mark.
Question 24
Answer: crystalsRight after the salt is dissolved in the water
What does Experiment 3 show growing?
you dissolve lots of salt into the water and watch the crystals form. So it basically teaches the kids about growing crystals.
Question says → You hear
to show how ... growteaches the kids about growing crystals
Why: The purpose is to teach how crystals grow. The gap needs a plural noun: crystals.
The trap: Salt is what you start with, not what grows. 'Form' and 'growing' both describe the crystals.
Besides cardboard and coloured pens, what does the colour wheel need?
Then you thread a piece of string through the middle. So we'd need some string as well. Yes, sorry.
Question says → You hear
cardboard, coloured pens and ayou thread a piece of string through the middle
Why: The string is added as an afterthought: 'we'd need some string as well'. After 'a', string or piece of string fits.
The trap: Cardboard is said first but is already printed. The circle and the six segments are what you draw, not equipment.
Question 26
Answer: lightWhen one speaker asks 'What's the principle behind it?'
Also accepted: white light / ordinary light
What does the colour wheel teach children is made up of colours?
It teaches them about how white light or ordinary light is made up.
Question says → You hear
to teach children about how ... is made uphow white light or ordinary light is made up
Why: The table copies 'how ... is made up', so the gap is light. White light or ordinary light are also accepted.
The trap: 'White' alone is wrong. The colours merging to show white is what you see; the lesson is about light.
Matching (A-H)
Questions 27-30
How to attack this block: Experiment 4 is the example, so you only match four. The speakers never use the box words: they say 'risky', 'tame', 'a fortnight', 'ambitious'. Translate each objection into a box option, and expect some options, like too messy or too noisy, never to fit.
Question 27
Answer: HStart of the second pass, 'Right, number one'
What is the problem with Experiment 1, the hovercraft?
don't you think it's a bit risky to get a group of eight-year-olds pushing each other around a classroom like that? Well, someone could get hurt.
Question says → You hear
too dangerousa bit risky … someone could get hurt
Why: 'Risky' and 'someone could get hurt' mean it's too dangerous, H.
The trap: Equipment is mentioned first, but as a plus: 'it doesn't need too much in the way of equipment'. So D is the opposite of what's said.
Question 28
Answer: BAfter 'What about number two? With the paper clips?'
What is the problem with Experiment 2, the paper clips?
It sounds tame enough. Yes, a bit too tame, if you ask me. I think it needs to be something a bit more active and interesting than that
Question says → You hear
too boringa bit too tame … something a bit more active and interesting
Why: Too tame, and they want something more interesting: it's too boring, B. They also worry the children won't enjoy it.
The trap: Too easy, F, sounds close, but it's the example answer for Experiment 4. The complaint here is about interest, not difficulty.
Question 29
Answer: EAfter 'what about the next one, number three?'
What is the problem with Experiment 3, the crystals?
we had to wait up to a fortnight before we saw any halfway decent results
Question says → You hear
too longwait up to a fortnight before we saw any halfway decent results
Why: Two weeks is far longer than the hour or two they have with the children, so it takes too long, E.
The trap: Dissolving salt in water might sound messy, A, but nobody says so. The only problem raised is time.
Question 30
Answer: CThe last one, 'what about number five?'
What is the problem with Experiment 5, the record player?
don't you think it's a bit ambitious for this age group? I mean, I don't want to start off something and then have to abandon it if they just can't cope with it.
Question says → You hear
too difficulta bit ambitious for this age group … they just can't cope with it
Why: Too ambitious for eight-year-olds, who might not cope, means too difficult, C. They fear they'd end up doing the work themselves.
The trap: In the first pass they said it needs 'quite a lot of equipment', which points to D. In this pass, though, the equipment is the attraction and the age group is the problem.
Experiment 5 needs a lot of equipment, and that was said in the first pass, so D looks right. But the objection now is that it's 'a bit ambitious for this age group' and the children 'just can't cope'. That's too difficult, C.
'A bit too tame' means not exciting enough. People confuse it with too easy, F, but that's the example answer for Experiment 4. They want something 'more active and interesting', so too boring, B.
Two chemicals are offered: rock salt or copper sulphate. One speaker isn't sure about copper sulphate, so they put down only rock salt.
Words from this recording worth keeping
ambitious(Experiment 1)
needing a lot of skill or effort to succeed
cushion of air(Experiment 1)
a layer of air that holds something up
dissolve(Experiment 3)
mix a solid into a liquid until it disappears
segments(Experiment 4)
equal parts that something is divided into
elementary(Experiment 4)
very basic and simple
tame(Problems with Experiment 2)
dull and not exciting
fortnight(Problems with Experiment 3)
two weeks
abandon(Problems with Experiment 5)
stop doing something before it's finished
Sit this test on Langujet, then come back
The full Cambridge 4 Test 4 listening paper with the real audio: all four parts, played once, marked the moment you finish. Already done it? Take it again and listen for the traps this page showed you.
Cambridge IELTS 4, Test 4, Listening Part 3. The recording, transcript and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts of the transcript only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full material, or sit the test on Langujet.
