Want to keep learning?

This content is taken from the National STEM Learning Centre's online course, Introducing Assessment for Learning. Join the course to learn more.

Skip to 0 minutes and 3 seconds [Teacher] So the first one’s solute. Can anyone tell me how we might use the word solute? All right, Daisy. What do you think? Daisy - Well, a solute is a liquid that you dissolve something into. [Teacher] OK so Daisy says a solute is a liquid that we dissolve something into. Would anyone like to challenge that? Does anyone agree? Does anyone disagree? Ross, what do you think? A solute is a liquid that we dissolve something in. Ross - I had the same idea. [Teacher] The same idea? OK, so Ross– Jay, you had a different idea? Jay - I just thought maybe it’s something to do about putting an egg in the salt water.

Skip to 0 minutes and 40 seconds [Teacher] OK, so put an egg in salt water. Right. So that’s– we’re going to look at the egg in the salt water in a sec. It has got something to do with that, though. So as we’re putting an egg in salt water, there’s something about the salt water that is a solute. So what do you think is about the salt water that is a solute? Molly, have you got any ideas? What is a solute? Molly - Is it when something’s dissolved in something? [Teacher] So when something is dissolved, So the solute therefore is– Molly - Salt. [Teacher] … the thing which dissolves. So for example, salt. Can anyone think of any other examples?

Skip to 1 minute and 9 seconds So salt is a good example of a solute. It is something which dissolves in water. Can anyone think of any other examples of a solute? So salt’s a good example of a solute. Can anyone think of any other examples? Yeah, Charlie.

Skip to 1 minute and 26 seconds Sorry, Richard. Richard - Yeah, sugar. [Teacher] Sugar. Good. OK, so when we put sugar into our tea, or if you’ve got sugar in water, that is a solute. Once you added our sugar to our salts and we’ve mixed it, is the sugar there’s still there? So we’ve put our sugar in our tea. It seems to have disappeared. We’ve put our salt into our water, it seems to have disappeared. Has it disappeared? No. What do you think? If you think it’s disappeared, put your hand up. No, it’s a real thing. It’s not disappeared. Right. What do you think, Nathan? Nathan - I think it’s formed a solution. [Teacher] You think it’s formed a solution. OK, fantastic.

Skip to 2 minutes and 0 seconds And that’s the second word, isn’t it? So once we’ve added our solute to our solvent– so the solvent is the liquid part we’re dissolving it in, we end up with a solution.

Skip to 2 minutes and 13 seconds Student A - The last question of the– I’ve done that wrong. I’ve done it really wrong. [Teacher] OK, so if you look at this here, to help us understand it, and look at that thing on the board, what it’s asking you– I’m sorry, Lauren. Lauren - Is the water able to get into the [INAUDIBLE]?? [Teacher] Yes, because if you look at the diagram on here, that is a partially permeable membrane Student B - Is that what that thing is, at the bottom? [Teacher] Yes. OK, so that’s a partially permeable membrane, so the water can get in. So that– Student A - Does this– But that can’t get– [Teacher] So what do you– what do you think it is? Go on.

Skip to 2 minutes and 41 seconds Well, yeah, it’s just water. Student B - Wait, so– So the water’s gone and– That gets into there and makes it– because this is too much of it, right? This is– [Teacher] Good. Student B - That’s the water that’s been added in round here, so that’s– [Teacher] Well, kind of. It’s all mixed together, but– Student B - But not as much as– concentrated as that. [Teacher] Well, it hasn’t equalised yet, because it’s still going. It’s still going up. Student B - Will it slide up? [Teacher] It will have, actually, if you were to leave it. So this is pure water, with no solute. Here is water with solute. So that’s a solution.

Skip to 3 minutes and 7 seconds So obviously if there’s no solute in here, this must be the what, in terms of solute concentration? Lauren - Well, higher. JL - Higher. It’s going to be higher, isn’t it? Because there’s no solute in here, but there is solute in there. So therefore the water’s going to move. Student B - Wait, so that increases the mass. Student A - Why does it say it– Student B - But it says, why is this– [INTERPOSING VOICES] [Teacher] So this is actually station two. I’m just here to help you have a look at it, OK? Station one is talking about the potato experiment, which is the other way round. All right. In station one– Student C (?) - Yeah, the solution– yeah.

Skip to 3 minutes and 44 seconds [Teacher] Yes. And remember, in solution one it’s the other way round. Around the outside we’ve got the concentration of the solution, OK? You can write that. Lauren - So that’s– [Teacher] Go on. [INAUDIBLE] But if the solvent’s going into it, then how does that make it [INAUDIBLE]?? Right. No, because the [INAUDIBLE]. Student C - It’s a potato. Because it’s got higher amount of sugar than the water, the potato is losing mass to try and like dilute the water– Lauren - Oh, so water comes out of the potato. [Teacher] Water comes out of the potato, and therefore it makes it lose mass. Try not to say drying, but it is water moving out.

Skip to 4 minutes and 16 seconds So if we put the potato, just like we put the egg, in the concentrated sugar solution, if we put the potato in the concentrated sugar solution, the water leaves the potato. And that’s why the potato, this one here, loses mass. [Teacher] OK, thank you. [Teacher] So we’ve had a really careful look on my table at the different kinds of foods that are available, and the different environments, so the different places that you’ve got to try and collect your food from. Which do you think is going to be your most effective beak, and why? Joel. Joel - The cup, because you can scoop up. [Teacher] OK, so you could scoop up quite a lot with a cup.

Skip to 4 minutes and 52 seconds Can anyone tell me, on Joel’s idea, which environment that might be quite difficult for? Have a quick look at your different environments. Student - That one. [INTERPOSING VOICES] [Teacher] OK, five, four, three. Where might Joel be challenged, if he’s just using the cup as a scoop? Dylan. Dylan - In the jugs. [Teacher] Yeah, in the jugs, in the beakers, in the little tube. Anywhere where it’s a small space. So scooping is one technique that is going to be a challenge in some environments. Anybody got a different idea of which one might be best? Connor. Connor - The cocktail stick. [Teacher] The cocktail stick. Why, Connor? Why do you think that will be effective?

Skip to 5 minutes and 33 seconds Connor - Because you can get these out of it. Because you can push it, and then– [Teacher] OK, I’m going to move Connor’s idea on. Which particular foods is the cocktail stick going to be effective for? I know we’ve talked about it, Amy, so I’m not going to pick you. I’m going to come over to Shauna. Go on. Shauna - Jellybeans. [Teacher] Why jellybeans, Shauna? What property have they got that’s going to make them– Shauna - It’s hard inside, and it doesn’t move about. [Teacher] OK, so how is that going to be helpful? Why is that going to be possible, using a cocktail stick? Lauren, do you want to whisper your idea to Shauna? Help each other out.

Skip to 6 minutes and 9 seconds Shauna - Jellybeans are soft. [Teacher] Because they’re soft, so you can squish them in. Is that what your idea, Lauren, that you can– anything that’s squishy? Lauren - And raisins, as well. [Teacher] And raisins, yeah. And there’s a couple of other things there. Student B - Yes I do, because I managed to get things out with– in tube and– [INAUDIBLE] [Teacher] And the low environment, as well. So you’ve actually got some [INAUDIBLE] down here. What about you, Joel? You think you could make it like this? Joel - No, I wanted that clip now. [Teacher] Why? What was it about yours that you don’t think – it was effective?

Skip to 6 minutes and 41 seconds Joel - When I kept blowing in to pick it up, pieces of biscuit kept getting into the my throat. [Teacher] Oh, so you were getting things down your throat. That’s not very nice, is it? Yeah, so it’s maybe not very effective at just the job it was doing. Do you like Maltesas? I do. [INTERPOSING VOICES] Student C - I done a good choice, because with the biscuit, you can just pick it up really easily. WM - So you’re happy with your choice.

Classroom talk

Watch and re-watch the four clips of teaching and learning from two classes of different ages. These involve whole class discussion and questioning, and group or paired work.

Think about how the teacher and student roles differ between the segments, and consider the implications for the conduct of whole class and group discussion. Don’t forget there are subtitles and a video transcript available to help you follow the discussion.

Here is an editable table [DOCX] (which also contains helpful information about the start and finish times of each segment) to summarise your findings.


Pick one of the four clips in the video. Draw out what you think the effective practices are that are being shown by the teacher. Summarise these in the comments below, making clear which clip you are referring to.

Share this video:

This video is from the free online course:

Introducing Assessment for Learning

National STEM Learning Centre