Hello, scientists.

My name is Mr. Wilshire, and in this lesson, we're going to be looking at temperature and evaporation.

This is the planning stage.

The outcome for this lesson is that, "I can plan how to investigate how temperature affects the rate of evaporation." As always, there's some keywords to consider as we work our way through this lesson.

The first is evaporation.

Next is temperature.

After that, affect.

And finally, variables.

Don't worry if you're not too sure what some of these words mean.

The definitions have appeared on the screen for you.

So you can pause the video here and recap before you move on.

The first part of this lesson is called Scientists Investigate Evaporation.

Sam and Jacob have been learning about evaporation.

Here's Sam and Jacob.

I wonder if you can remember what evaporation is.

Pause the video here and have a quick discussion.

Restart when you've done that.

How did you get on? Can you remember what evaporation is? Well, evaporation is the change of state from a liquid to a gas.

Did you say something similar? Evaporation is the reason that washing dries, wet surfaces become dry, and puddles seem to just disappear.

They're not disappearing though, are they? They are evaporating.

Here you can see an image of a wet surface and an image of a puddle.

I wonder if you've ever noticed these things before.

Evaporation of a liquid can take place at any temperature.

Water in a saucer on a kitchen worktop will evaporate even without being heated or put in sunlight.

Hmm, I wonder why.

How fascinating.

I think I'm gonna try that at home on my kitchen surface.

Stop and think, true or false? Evaporation of a liquid occurs only at high temperatures.

The correct answer here is false.

Evaporation of a liquid can take place at any temperature.

Sam says, "The washing on a line dries more quickly when it's sunny and hot.

Why is this?" Sofia says, "I think light from the sun speeds up evaporation." And Jacob says, "I think heat from the sun speeds up evaporation." What do you think? Is it light or is it heat? Have a quick discussion about this.

Restart when you've done that.

So what did you think? Is it due to heat or is it due to the light? Let's find out more.

Scientists investigate how temperature affects how quickly a liquid evaporates to a gas.

Ah, so maybe it was more to do with the heat than it was to do with the light.

In ancient Greece, Aristotle observed that water left out in the sun evaporated faster than water in the shade.

Galileo, who lived from 1564 to 1642, noticed that water in a heated container evaporated faster than water in an unheated container.

Hmm.

There's an image there of Aristotle and an image of Galileo.

Modern scientists observe and measure evaporation in natural settings.

Here you can see an image of them doing exactly that with some different scientific equipment.

Now they measure evaporation from lakes and rivers in different climates.

They also investigate evaporation in the laboratory where they can control the temperature.

I wonder if you've ever done any experiments like this before as well, trying to evaporate different waters at different temperatures.

You may have tried this outside or maybe even at home.

You may have even seen some water evaporating and then wondered what had happened to it.

Stop and think.

Which of these things can affect how quickly a liquid evaporates to a gas? Is it noise, is it temperature, or is it light? The correct answer here is temperature.

The temperature can affect how quickly a liquid evaporates to a gas.

Here is Task A.

Discuss with a partner how you might find out how temperature affects how quickly liquid water evaporates.

You need to then record your ideas by making some notes.

There you can see an image of some water evaporating into a gas, and of course, the thermometer there as a way to investigate the type of temperature it is at.

So best of luck discussing this task.

Restart the video when you've done that.

I wonder if your ideas are similar to this.

"We decided that we could leave saucers of water in different places, one in a fridge, one in a radiator, and one on a worktop.

We'd measure the temperature in each place and the time it takes for all the water to evaporate.

We could then compare how quickly the water evaporated in each place." Hmm.

I wonder here how they could make this a fair test.

They're going to need to make sure that they use the same amount of water.

They're also going to need to make sure that they are careful that they use the same type of container, aren't they? I wonder what else you can think of.

The next part of this lesson is called investigating evaporation.

Sam and Jacob would like to investigate evaporation.

They know that temperature effects evaporation, but would like to make some measurements to demonstrate this.

They've talked about some ideas, but have not yet decided exactly what they might do.

So remember, when you're investigating something, it's a very good idea to have a question, isn't it? You need to know what it is that you're investigating.

So what is their question going to be here? Wonder if you can pause the video and have a discussion.

Think about a good question for them to use, and then restart when you're ready to move on.

So what could that question be? I wonder if you said something about evaporation or if you said something about temperature.

I wonder if it is similar to what Sam says here.

"Does the temperature of the room affect the time taken for the water to evaporate?" So what could they do? Jacob says, "We could put one small dish of water in the sun and one in the shade and then see which evaporates first." Sam says, "We could put one wet flannel in a hot place and one in a warm room and one in a cold room and see how long they take to dry." Jun says, "We could put one beaker of water in the fridge, one in the middle of a room and one on a radiator and see how long it takes for the water to evaporate." So which of these children has the right kind of idea about the type of investigation that they're going to do? They know the question they're trying to answer, but which of these statements here is the best one? Have a discussion about this and move on when you're ready.

How did you get on? Hopefully you've had a good chance to discuss which of these is going to be the best way to go about their investigation.

Let's see what the children chose.

The children decide to try Sam's method.

She said, "We could put one wet flannel in a hot place, one in a warm room and one in a cold room and see how long they take to dry." This might get some different results to just putting water in a beaker or a container, won't it? They know that when they plan an investigation, they need to think about variables.

Ooh, I think we've mentioned that before, haven't we? I wonder if you can remember from the earlier task.

Variables are things that can be changed.

They could be measured, they could even be kept the same in an investigation.

So what variables could there be with Sam's method? I've mentioned some before, so I wonder how well you were listening earlier.

Pause the video here and discuss.

Restart when you've done that.

So what kind of variables are there going to be with Sam's method here? Let's find out more.

Now remember, the inquiry question is, does the temperature of the room affect the time taken for water to evaporate? So the variable that the children will change is the temperature of the room.

Are they going to have any other variables in their lesson? Are they going to be able to change anything else? Well, no, because to make it a fair test, they should only be changing one thing.

So the variable that the children will observe and measure is the time taken for the water to evaporate.

So they're not going to change the amount of water.

They're not going to change anything else apart from the temperature.

The children keep all the other variables the same, including the size of the flannel, the starting temperature of the water, the volume of the water on the flannel, and the way that the towel is hung on the rack, is going to be hung flat.

They're also going to keep the windows and the doors closed so that no wind or any other temperature can get inside as well.

Here you can see a wet flannel drying on a rack.

I wonder if you've ever dried a towel or a flannel in this way as well.

Have you found that laying it flat is the best way to do that? So all of these things are going to stay the same, aren't they? The children are going to control the amount of temperature in the room.

They're going to control all the other aspects of this investigation as well.

Remember that there might be some things that are completely out of their control.

They might find that if they're using the sun to out dry something, what if the clouds come over as well? That's why hopefully they're going to do a lot of their investigating inside.

They also need to try and stop other people from moving these flannels too.

It's also going to be a good idea to start this investigation at the beginning of the day or otherwise, they're going to run out of time if it's home time.

Also then that runs a risk of somebody cleaning up the classroom at the end of the day and moving all their investigation as well.

Let's stop and think.

Blank are things that can be changed, measured, or kept the same in an investigation.

Is it thermometers, variables, or materials? The correct answer here is variables.

Variables are things that can be changed, measured, or kept the same in an investigation.

Let's stop and think again.

How many variables should be changed in a fair test investigation? Is it zero, one, two, or it doesn't matter? The correct answer here is one.

Only one variable should be changed in a fair test investigation.

Here is Task B.

You now need to look back at your ideas from the first task.

Now either develop this or use one of the children's ideas from earlier in the lesson to plan an investigation to answer this inquiry question.

Does the temperature of the room affect the time taken for the water to evaporate? So then you need to have a go writing or drawing your ideas here, and you need to include the equipment that you're going to need, what you will do, what you will change, what you will observe or measure, and what you will keep the same, and any other variables that will be very difficult to control.

Remember, I said that the time of day is going to be quite difficult to control, especially if it's very late in the day now.

So you may, if you are going to run this investigation, want to do it tomorrow if it's later on in the school day.

Also, it's gonna be very difficult to control anybody coming into the classroom as well.

You certainly can't control that.

So you need to think about what you're going to do and how you're going to warn people that there is an investigation or an experiment going on.

Think about in a lab, they would have different key cards and different signs up, telling people what is going on.

That's hopefully then going to tell anybody cleaning that area that there's an investigation that should not be disturbed.

So don't forget to include all of those items there and have a go developing these ideas or your own.

Best of luck with your task.

Restart when you've done that.

Maybe your investigation ideas looked a little bit like this.

Remember though, this is going to differ depending on the type of investigation that you're doing and the type of method that you chose to do, especially if you've chosen to follow your own method.

So here are some ideas.

The first step there is to take three identical flannels and find and record the mass of each.

That means you need to weigh them.

Two, spray 25 cubic centimetres of water onto each one.

You could use a spray bottle for this, making sure that the spray bottle is filled up with exactly that amount.

Alternatively, you could use a little syringe if you wanted to get a really accurate amount of water.

Three, find and record the new mass of the flannel.

Remember, all that water on the flannel is now going to make it a little bit heavier than before.

So you need to weigh it again, just to make sure that they all weigh the same.

Four, put one flannel in a hot room, one in a warm room, and one in a cold room.

Remember, you're going to need to use a thermometer to measure this beforehand.

So make sure that you've done some checking first and really good thinking about where you're going to place a flannel before you start the investigation.

Five, measure the temperature of each room and add it to the table.

So the temperature needs to be controlled there, doesn't it? They need to try and stay the same the whole way through the investigation.

Six, every hour, find and record the mass of each flannel.

Seven, continue for four or five hours and compare the results for each room.

Four or five hours is a long time, so definitely not an investigation to start at the end of the school day.

So you're going to need three flannels, water in a spray bottle or a syringe, a timer, scales, thermometers, and three rooms of different temperatures.

The variable that you're going to change is the temperature of the room.

And remember, in this investigation, you're going to be weighing the flannels.

This is going to tell you if it's lost any of that mass, which means that the water has started to evaporate.

The variables that we'll keep the same are the types of flannel, the size of the flannels, the volume and the temperature of the water added to each flannel.

The variable that they're going to measure is the mass of each flannel every hour.

So let's summarise our lesson.

Evaporation can take place at any temperature.

Scientists investigate how temperature affects how quickly a liquid evaporates to a gas.

And a comparative test investigation involves controlling variables so that only one thing is changed.

Well done for completing that lesson.

There is some really good ideas about how you can investigate evaporation there.

So hopefully if you do go through to investigate this and use the method that you created, you'll have a good idea as to how temperature can control the evaporation that happens.

I've been Mr. Wilshire.

Thank you very much for listening.