Basic science: understanding experiments
Basic science: understanding experiments

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Basic science: understanding experiments

2.1.1 The experiment

Have you got all the equipment you need? Follow Janet’s instructions in the video (or use your activity booklet [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]  PDF) to conduct the experiment.

Download this video clip.Video player: ou_futurelearn_experiments_vid_1009.mp4
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Transcript

JANET SUMNER
In this experiment, we're going to investigate the properties of liquids and observe how they behave under different circumstances. Now, we all know what happens when you drop an ice cube into a drink. It floats. But is this the same reaction that happens with all liquids?
That's what we're going to find out. For this experiment, you're going to need your freezer, an ice cube tray, and a selection of liquids. Now, there are three compulsory liquids that we're all going to test. That's plain ordinary tap water straight out of the tap, salt water, which again is just tap water but I've added a couple of tablespoons of salt to make a saline solution, and olive oil.
But we're also going to ask you to test a fourth liquid of your choice. Now, you can be as creative as you'd like. I did think about maybe milk or washing up liquid. But I've actually chosen runny honey because it seems to have a similar consistency to the olive oil, so I want to find out if it's going to behave in the same sort of manner.
Before you start the experiment, make sure you print off the ice cube tray diagram from your study journal. And then label very carefully which liquid is going into which section of the ice cube tray. So I've got water, salt water, olive oil, and honey. And I'm actually going to label my ice cube tray as well.
So now I'm going to fill up the individual compartments within the liquids, first the tap water. I overfilled that a bit. Just let it out. Then the salt water. Now the olive oil. And finally, going to do my last one with the honey. And this will then go into the freezer.
I'm also going to fill four glasses with the same liquids and make sure that they're clearly labelled as well. I've got a sheet of plain paper. Do them in the same order, tap water, salt water, olive oil, and honey.
And I'm going to fill the glasses up now. So some tap water. Salt water. Add the olive oil. And the honey.
Well, this has been in the freezer overnight, and they all seem to be frozen, even the salt water and the honey, which I'm surprised about. But we can comment on that in the discussion afterwards. So now I'm going to remove the frozen cubes and drop them in the same liquid, if I can get them out, and see what happens.
So that's the tap water into tap water, and that floats. Well, that was expected. Now let's do salt water into salt water. Oh, and that floats as well. Now the olive oil. It's a bit more difficult to get out. There it is.
And I'm going to drop the frozen olive oil into the liquid olive oil. Oh, and that's sinking right to the bottom of the glass. So that's a different reaction. Right, now let's try the honey last of all. Now, if I can get the honey cube out, [GROAN]. It's really sticky, but it's coming out.
All right, see if I can pull it out. It is frozen, mostly. OK, let's see what happens when the honey goes into the honey. Well, that seems to be sinking as well, but much more slowly than the olive oil. But I think that's because the honey is much stickier and more viscous. But it is sinking very slowly.
Well, that's my observations recorded. Now it's time to join the online discussion. Share your results, and we'll interpret and understand what we've just seen.
End transcript
 
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As with any science experiment, it is important to keep detailed notes and to label your ice tray and glasses so you can keep track of the different parts of your experiment. Your activity booklet has a diagram of the ice cube tray to help you with recording this information.

Last week, you learned that variables are the factors than can be controlled, changed or measured in an experiment. What variables can you think of that might alter these results? Write these down, they might be useful later. Remember, this is an observational experiment – try taking photographs of your experiment. This will help you to remember the results later and allows you to share your results with your fellow learners.

You will have the opportunity to discuss your results in the next section.

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