# Selecting Science Experiments for Eight-year-olds: answers and explanations

Cambridge IELTS 4, Test 4, Listening Part 3

Source: Recording, questions and answer key from Cambridge IELTS 4, Test 4, Listening Part 3. © Cambridge University Press & Assessment. Used for educational practice. Explanations and evidence notes are written by Testmigo.

## Answer key

| Q | Answer | Proof |
| --- | --- | --- |
| 21 | 20 balloons | you only need 20 balloons and a table. |
| 22 | units of measurement | It's supposed to demonstrate the importance of having fixed units of measurement. |
| 23 | rock salt | you need rock salt or copper sulphate. ... Well, just put down the rock salt then. |
| 24 | crystals | So it basically teaches the kids about growing crystals. |
| 25 | string | Then you thread a piece of string through the middle. ... So we'd need some string as well. |
| 26 | light | it teaches them about how white light or ordinary light is made up. |
| 27 | H | don't you think it's a bit risky to get a group of 8 year olds pushing each other around a classroom like that? ... Well, someone could get hurt. |
| 28 | B | It sounds tame enough. ... Yes, a bit too tame if you ask me. |
| 29 | E | we had to wait up to a fortnight before we saw any halfway decent results. |
| 30 | C | But don't you think it's a bit ambitious for this age group? ... if they just can't cope with it. |

## Why these answers are right

**21. 20 balloons.** The equipment cell for the hovercraft experiment ends with "and a table". Mike says you only need 20 balloons and a table, with no engines, so "20 balloons" fills the gap; the number is part of the answer and keeps it within the limit.

**22. units of measurement.** The purpose of the paper clip experiment is to show why we need standard something. Mike explains that clips differ in length, so it demonstrates the importance of fixed units of measurement. "Standard" paraphrases "fixed", leaving units of measurement as the answer.

**23. rock salt.** You need the material used with a jar of water. Mike offers rock salt or copper sulphate, Sue is unsure about the second, and Mike tells her to just put down the rock salt. So rock salt, or simply salt, is the answer here.

The why and the trap for questions 24 onwards are free with an account on the [answers page](https://testmigo.com/ielts/listening/selecting-science-experiments-for-eight-year-olds/answers).

## Transcript

**Announcer:** Section 3, you will hear a conversation between two students who are studying to be teachers talking about science experiments.

**Announcer:** First, you have some time to look at questions 21 to 26.

**Announcer:** Now listen carefully and answer questions 21 to 26.

**Mike:** Hi, Sue.

**Sue:** Hi, Mike.

**Sue:** So what happened to you last week?

**Mike:** Oh, I was sick with the flu.

**Mike:** What's this I hear about a big assignment we've got to do?

**Sue:** Oh, well, basically, we've got to find two science experiments to do with a group of eight year old children at the local primary school.

**Sue:** And we've got to complete it by the end of the week.

**Mike:** Hmm. That sounds like hard work.

**Mike:** Where are we supposed to get the ideas for these experiments from?

**Sue:** Well, I managed to get hold of 2 books from the library.

**Mike:** Oh, well done.

**Sue:** How about if we take a look at the experiments in this book first, and see if anything looks suitable?

**Sue:** I can make notes as we go about equipment and the purpose of the experiments.

**Mike:** OK.

**Mike:** Let's see, um, the first experiment is called 'Make your own hovercraft'.

**Mike:** Ha, which sounds very ambitious.

**Sue:** Ha ha ha.

**Mike:** Mind you, you only need 20 balloons and a table.

**Mike:** You don't need any special engines or anything like that.

**Sue:** What do you do with it all?

**Mike:** Uh. You blow up the balloons, and you balance the table on them, upside down, of course, and the kids get to ride around on it.

**Mike:** You know, the other kids sort of push them around the room.

**Mike:** The main purpose is to show how hovercrafts work, and how things hover around on just a cushion of air.

**Sue:** OK, that doesn't sound too bad.

**Mike:** OK, ready for number two?

**Sue:** Uh-huh.

**Mike:** Now this one is called 'Unusual Measures of Lengths', and you basically use lots of paper clips.

**Mike:** The kids go around the class measuring things, you know how long the desk is, and that sort of thing.

**Mike:** Um. And then they all compare their answers.

**Mike:** Uh. And basically, because not all paper clips are the same lengths, they should come up with some strange answers.

**Mike:** It's supposed to demonstrate the importance of having fixed units of measurement.

**Sue:** Yeah, that's not bad.

**Mike:** OK, now for No. 3, you need rock salt or copper sulphate.

**Sue:** Oh, I'm not sure about that.

**Mike:** Well, just put down the rock salt then.

**Mike:** Um. Apart from that, you only need a jar of water.

**Mike:** And basically you dissolve lots of salt into the water, and watch the crystals form.

**Mike:** So it basically teaches the kids about growing crystals.

**Sue:** Yeah, I suppose it would be nice to grow something.

**Sue:** Hmm, let's move on and have a look at No. 4.

**Mike:** OK, this one is called 'Spinning Color Wheel'.

**Mike:** It looks like you get some cardboard and draw a circle on it.

**Mike:** Divide it into 6 equal segments, and color each one in, using different colors.

**Mike:** Then you thread a piece of string through the middle.

**Sue:** So we'd need some string as well.

**Mike:** Yes, sorry.

**Mike:** Um. And you spin the wheel around, and if you can get it spinning fast enough, hopefully the colors all merge and show up as white.

**Sue:** Oh, I didn't know that.

**Sue:** What's the principle behind it?

**Mike:** Well it's pretty elementary physics really, it teaches them about how white light or ordinary light is made up.

**Sue:** Hmm, well that doesn't sound too bad.

**Sue:** Now, there's only one more left in this book, isn't there?

**Sue:** What does that one say?

**Mike:** Um. Well, it's another one where they'd get to make something.

**Sue:** Sounds very interesting.

**Mike:** You need quite a lot of equipment actually, a hand drill.

**Mike:** An old record, a pin or needle, some paper, and a bolt.

**Sue:** Hmm, go on.

**Sue:** What do they have to do?

**Mike:** Well, they basically make a record player.

**Mike:** The main idea is to teach them about recording sound.

**Mike:** But hopefully they'd also see that you need motion and an amplifier to make the sound heard.

**Sue:** OK, well, it does sound interesting.

**Sue:** Shall we go through all of those again and decide if any of them are going to be suitable?

**Announcer:** Before you hear the rest of the conversation, you have some time to look at questions 27 to 30.

**Announcer:** Now listen and answer questions 27 to 30.

**Mike:** Right, No. 1, I thought this one sounded nice.

**Mike:** There'll be lots of activity, and it doesn't need too much in the way of equipment.

**Sue:** Yes, that's true, but don't you think it's a bit risky to get a group of 8 year olds pushing each other around a classroom like that?

**Sue:** Well, someone could get hurt.

**Sue:** No, I don't like the sound of that one at all.

**Mike:** Hmm. Maybe you're right.

**Sue:** What about No. 2, with the paper clips?

**Sue:** It sounds tame enough.

**Mike:** Yes, a bit too tame if you ask me.

**Mike:** Hmm. I think it needs to be something a bit more active and interesting than that, don't you?

**Sue:** Yes, I suppose you're right.

**Sue:** We won't get a very good mark if the children don't actually enjoy the experiments, and I suppose we could turn them off science for good.

**Sue:** Well, what about the next one, No. 3?

**Mike:** Now, I quite like the idea of this one.

**Sue:** Yeah, so do I.

**Sue:** But I seem to remember when we did it at high school, we had to wait up to a fortnight before we saw any halfway decent results.

**Mike:** Oh, yes.

**Mike:** Well, that won't be any good then.

**Mike:** We'll only see the kids for one or two hours at the most.

**Sue:** Yes, and we have to do the experiments and write up our results within a week.

**Sue:** So that one won't do at all.

**Mike:** OK, well, what did you think of No. 4?

**Sue:** I like the idea of it, but do you think it will be a bit elementary for them?

**Mike:** Well, they are only eight, you know.

**Sue:** I know, but you know what I mean.

**Sue:** Don't you think the activity itself is a bit babyish?

**Mike:** Hmm. Maybe you're right.

**Sue:** They might have fun, but I mean cutting out a circle and coloring it in.

**Mike:** OK, well what about No. 5?

**Sue:** I thought this one sounded a bit too good to be true -

**Sue:** great equipment.

**Mike:** Yeah.

**Sue:** But don't you think it's a bit ambitious for this age group?

**Sue:** I mean I don't want to start off something and then have to abandon it, if they just can't cope with it.

**Sue:** I could see us ending up doing just about all of the work for them.

**Mike:** I guess you're right.

**Mike:** Oh, well, maybe we could store that idea away for later.

**Sue:** Yep, let's hope this second book has something better.

**Announcer:** That is the end of section 3.

**Announcer:** You now have half a minute to check your answers.

[Practice Selecting Science Experiments for Eight-year-olds](https://testmigo.com/ielts/listening/selecting-science-experiments-for-eight-year-olds)