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Skip to 0 minutes and 3 seconds KAREN BRUNYEE: Hello, and welcome to the question and answer session for this primary chemistry online course. I hope you’ve really enjoyed the three weeks on the course, and that you’ve got a lot of ideas from it, and it has helped you think about the subject knowledge around primary chemistry. We’re going to have a look at a few questions that people have put into the final step of the course here. And the first question that we got asked was from Saira, and Saira asked– so these are really quite complex subject knowledge questions that she was asking. And she said, well, how do you explain the concept of pressure and how it affects the temperature that water boils?

Skip to 0 minutes and 44 seconds Now, this isn’t really a primary idea. My colleagues in secondary team actually deliver this part of the learning, but I thought, as the question has been asked, I’ll see if I can find the answer for you. So, basically, for any liquid to turn into a gas, into the vapour, it needs to meet that atmospheric pressure, so the pressure needs to equal– the vapour pressure needs to equal the atmospheric pressure. To do that at sea level, so where most people are, is it takes 100 degrees temperature for the water to boil, therefore, turning into a gas. When the atmospheric pressure is less, it takes less energy for the liquid to boil.

Skip to 1 minute and 33 seconds So for example, at 10,000 feet, the atmospheric pressure is a lot less, so, therefore, it only takes 90 degrees for something to boil– now, well, water we’re talking about here. There is an investigation that you can do. It is very secondary investigation that my colleagues talk about, where you have a bottle. You add boiling water to the bottle, add a thermometer, and then seal it and remove the air. So you need a vacuum pump to remove the air out of there. And what you should notice is that the water begins to re-boil. And if you look in that thermometer, it should be boiling at a much lower temperature, and that’s because the pressure applied is less.

Skip to 2 minutes and 18 seconds Therefore, you need less energy, and it can boil at a lower temperature. I hope that’s answered your question, Saira. Now, Saira also asked the question about, why does water boil much quicker if you add a lid to a pot? Now, we all know this, don’t we? When we’re making out tea, if we put a lid on our pans, it’s much quicker. Basically, this is due to the fact that if you’re putting a lid on, you remove the cold air getting into your pan, so you haven’t got that convection of cold air getting in and affecting the temperature of the water. So, again, it takes less energy to boil.

Skip to 2 minutes and 57 seconds Also, by putting on the lid, the convection is much smaller, isn’t it? So you’re just getting the water boiling, evaporating, condensing on the lid, and then coming back down, and that is in a much smaller space. And, basically, by the time it’s evaporated, condensed, it’s already reaching, again, that temperature where it can evaporate again, so creating that vapour. So it’s a much quicker and more energy-efficient way of boiling water. A third question came from Grant, and grant asked a really lovely question. His question is, do you have any imaginative and creative activities that could be used for older primary or more able that need stretching?

Skip to 3 minutes and 40 seconds So I had a think about it, thought about it, the kinds of things that I would have done with my older children or those children that had grasped the concept we’re working on. And, basically, it’s all about context learning and problem solving. So for example, I had a year three class, so ages 7 and 8, and we were looking at dissolving. So we tried salts, and sugar, and all sorts of different things. And I just sent them the problem of– so there’s a chef, and the chef works in a country where they have banned salt. They say, you’re not allowed salt in anything.

Skip to 4 minutes and 15 seconds But he’s a great chef, so he wants to add salt to his food to make it taste. He thinks that’s the best food he can make. So he has to find a way of getting his salt past the people on the borders, and the children were set that challenge. And by the end of the session, I would have expected them to explore different ways of fooling the censors so that it could get– so that he could get his salt through. So the children– we had explored dissolving. They knew the concept, and then I set it up as a challenge.

Skip to 4 minutes and 46 seconds Now, a really good way of doing this a little bit further, so maybe with your older children, once they’ve explored dissolving, and filtering, and evaporation, and things like that is to do it through an industrial context. So there’s a company called CIC, who are based at York University, who’ve produced a lot of resources around working with industries and about putting science learning into context. And the one I’m talking about here is this resource here called A Pinch of Salt. They’re all downloadable for free from their website. And this one looks at the salt industry and the different ways that it’s used, things like salt on the roads, salt in food, salt in chemical processes.

Skip to 5 minutes and 32 seconds And one of the activities is called “Salt My Chips.” Now, if you’re from England or the UK, you’ll definitely know about lots of salt and vinegar on your chips. And in this activity, the children are given rock salt, so the salt you might get from the bins when you’re in the winter, when you’re trying to melt the ice on the roads. So they’re given a piece of, a bit of this, and then they have to, by the end of the session, have worked how to get white salt crystals from this rock salt. Now, the rock salt is full of impurities, and it’s got rocks in it, and dirt, and other things.

Skip to 6 minutes and 10 seconds And what I would do with the children is we’ve done all the pre-learning, so they know about the dissolving, filtering, sieving, evaporation, and all those parts. And then I would expect– I’d just say to them, OK, this is your challenge. By the end of this lesson, you need to have pure white crystals at the end. And then they will go away and explore that. The amount of support that you give to those children in your class can differ. You maybe expect the more able, the ones that really understood the concepts, to just work independently and get it finished, and you might give more support to others in the class.

Skip to 6 minutes and 49 seconds So that’s a really good way of doing it through a context. And as I say, all of those resources are downloadable. I’ve also done a really nice activity around visiting a sewage works. So here in the UK, you can go to water companies and go on visits, but if you want to do it just online, you can look at how sewage works work. And then ask the children, OK, so get some dirty water. So maybe you ask them, what kind of things might go down your sinks? So think about your kitchen.

Skip to 7 minutes and 19 seconds You might have cereal, milk, tea, maybe some dirt from when you’ve washed hands, bit of flower, all sorts of things like that, and create this mess, maybe, in a bowl. And say to them, by the end of this lesson, the group that have produced the cleanest water will be the ones that have worked really hard for the sewage company. And then maybe write to that sewage company and say, this is the best philtre that we’ve created. So, again, just doing it through a context is one of the best ways of challenging them, problem-solving, giving those children those ideas.

Skip to 7 minutes and 57 seconds Other places to get resources– the Teach Chemistry website from the Royal Society of Chemistry has some brilliant activities and links in there. I personally like the kitchen concoctions ones, where you look at kitchen foods and things like that, like sherbet, popping candy, and you look at the chemistry behind it, and then the children have a go at making it. And, again, I would set those as problem-solving. So I’ve done it where the company have lost the recipe for their sherbet, and they have to– the children have to recreate the recipe. I don’t give them guidance.

Skip to 8 minutes and 31 seconds It could be a bath bomb company, and you need to make the bath bomb that bubbles the best in the bath, or change the colour, lots of things like that. And, finally, if you look on the CREST Awards site, they have some really lovely activities where the children can work through them independently. So depending on the age of your children, you might look at superstar or discovery. And, again, it is a problem, and the children work through, and they have to apply their science learning, so lots of ideas out there for challenging those children that have grasped the topic, and you want to extend them. Final question came from Erin.

Skip to 9 minutes and 15 seconds And Erin asked, how might you teach more about types of mixtures and separation of mixtures? Well, Erin, that’s a lovely question. I would usually start with a really simple task of just putting out some mixtures, so maybe two things, three things, more, depending on how many I want the children to explore. So they might– and I might say, OK, I want you to– this is a mixture. So a mixture is, obviously, two things that haven’t created a solution. Can you separate? So it could be as simple as picking things out, so Cheerios and flour. Let’s pick the Cheerios out.

Skip to 9 minutes and 51 seconds I might then add some metallic things, so some nails, and then they have to use a magnet to explore, and paperclips, and things like that. I’ve always found if you just put things out for the children and let them explore– so for example, I had a year five and six class, so these children years, ages 10 and 11, and some of them had never explored sieves. So I just put the sieves out on the table and gave them the activity to, what will be removed in the sieve? What will be left behind? What will go through? Then I’ll up the challenge. So I might have coffee grinds, and sand, and nails, and salt, salted water.

Skip to 10 minutes and 36 seconds And say, right, at the end of the lesson, you need to have everything separated. These are the things I’ve put in there. Can you separate them? Can you find a way around that? So similar to their pinch of salt activity, where they had the rock salt, you need a finished product, but this one I want all of the five things I’ve put out there. There is a wonderful, wonderful resource from a charity called Practical Action called Ditch the Dirt– again, free from their website– where they ask the children to think of problems within developing countries, and they have to develop a water philtre. So the children are given the instructions for how to build a water philtre.

Skip to 11 minutes and 16 seconds You create some dirty water, maybe just a bit of mud and water, and then they use the resources to build their own water philtre. At the end of the session, it’s the group that have produced the cleanest water. So at the end of making our water philtre, maybe get the children, just as a bit of an extension, to create a serverless still. And you might have seen these is survival programmes, where they’re trying to get some water in a place, in an place where there hasn’t been any rain.

Skip to 11 minutes and 44 seconds And so what I’d get the children to do is have a large bowl, and into the large bowl I’d put the dirty water or the water we filtered that’s not quite as clean as we would want it to be, and then put a glass or a cup in the centre of the bowl. You then pop a cling film over the top, and seal it, and I quite often put a pebble or a marble in the top just to create a little bit of a downward slope, and leave it somewhere warm. Then the dirty water will hopefully– in the warm place, it will evaporate up. So you’ll get that convection.

Skip to 12 minutes and 17 seconds It’ll evaporate or condense onto the cling film, and then it will, the water droplets will run down into that cup that’s in the centre, and then you’ve got quite clean water. Again, possibly, I wouldn’t ask the children to drink that because it doesn’t remove microbes, but it’s a good way of cleaning that filtered water, and there’s an end product, and there’s a bit of an extension. It’s a lead into what they do in secondary, when they’re looking at the evaporation and the distillation. You know it’s the first step, and it’s quite a nice one to do, maybe if you’re doing at-home learning and things like that. So it’s good on a warm day.

Skip to 12 minutes and 59 seconds One of my favourite ways, Erin, to do things around separation, and mixtures, and things like that is actually to make density columns. Now, it’s one of those things that is quite challenging, or it can be an easier one, but it’s all about those– not creating mixtures. It’s about creating separation. Easiest way to do that is ask the children to explore things that are in their kitchen cupboards or the bathroom cupboards, so things like honey and oil. So start seeing, do they separate out? What will go at the bottom? Things really heavy, high saturation point will go right to the bottom, things like syrup. The higher up you get, so that the less dense, you’ll get those nice columns.

Skip to 13 minutes and 45 seconds And I set it as a challenge to my children, so the older ones, is to say, OK, you’ve only got one ingredient, so in this case sugar, and I need you to make a density column to show that, a nice rainbow. So here’s one I made earlier this morning. Hopefully you can see it, absolutely beautiful. And all it is different concentrations of sugar solution. So I have a very saturated solution down here at the bottom, and then in each one, I’ve put less sugar into my solution, and then added food colouring in so you can see the bands. And that’s a really nice challenge to set for children. We don’t want to create a solution here.

Skip to 14 minutes and 30 seconds Well, we do, a sugar solution. But we don’t want our sugar solutions mixing because, obviously, if their mixing, we’re going to get a sludge, and we’re going to get a horrible colour. And here, you can see the definite bands, the rainbow bands there. And for some children, I might, say, tell them how much sugar to put in, how much water. So here’s my– these are my things that I was busy making up. So this one, I had 20 grammes of sugar in 25 mils of water, so that’s quite saturated. I can actually see at the bottom, I’ve got quite a lot of sugar that hasn’t dissolved.

Skip to 15 minutes and 7 seconds And my final one– so each time I removed 5 grammes of sugar from my water. In this one, the yellow one that was at the top of my column, there’s no sugar at all. So that’s just pure water. And then ask the children, can they build that? I might give them a recipe, or I might just ask them to explore. So the challenge is there. So, again, that’s looking at saturation points, density, viscosity, all those sorts of things that you can explore with the children within that context.

Skip to 15 minutes and 40 seconds Again, I would just, if you’re looking for activities like this, places to visit, obviously, the STEM website, if you have a look on there, and you look under the chemistry programmes of study there, there’s some lovely activities. The Royal Society of Chemistry, their Teach Chemistry website, they’ve actually got some demonstrations where they show you some of these really nice separation and filtration activities. So have a look, but, again, like I was saying earlier, if you can set them in a context, set them as a problem-solving activity, it will stretch and challenge those children. So that was all the questions we got asked. I hope those have helped you and added a little bit more to your subject knowledge there.

Skip to 16 minutes and 22 seconds We’ve really enjoyed working with you on this online course, and it would be great to see you again on another of our online courses. If you haven’t explored the physics one, that one is online at the moment. Our Getting Started, Primary Science looks at the working scientific aspects of the primary curriculum. And coming up in the very near future, there will also be an online biology course that you could explore. Thanks, again.

Q&A with course educators

On all courses from STEM Learning we provide a question and answer (Q&A) session. This is your opportunity to discuss your understanding of the course content, ask a question about your teaching context or explore an issue in more detail.

Karen recorded her responses to a selection of your questions. Karen has provided a wealth of teaching suggestions and links to resources. A transcript is currently being processed.


Karen also demonstrates a rainbow density column near the end of the video.

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This video is from the free online course:

Teaching Primary Science: Chemistry

National STEM Learning Centre