Hello, my name's Mrs. Niven, and today we're gonna be talking about scientific methods in the context of dissolving as part of our topic on solutions.

Now, it's very likely that you've come across scientific methods in some of your previous learning, and what we do in today's lesson will definitely help you as you go forward doing various experiments throughout your journey in science.

So by the end of today's lesson, you should be able to identify features of a good method and use those to help you improve a method that will help us to investigate dissolving further.

Throughout this lesson, we'll be using some keywords, and those include method, command word, repeatable, and reproducible.

Now on the next slide, the definitions for these keywords are provided in sentence form, and you may wish to pause the video here to read through those definitions or to perhaps jot them down so you can refer to them later on in the lesson.

Today's lesson, we'll look at two main aspects.

The first one is features of a good method, and then we'll look at how we can include repeatability and reproducibility into those good methods as well as what is the difference between the two.

So let's get started by looking at features of a good method.

Now, scientists are naturally curious about the world around them.

In fact, we're all scientists.

Whether you're doing it consciously or not, people are questioning their observations and what they see around them.

It's just people who go by the title of scientists have agreed to investigate those observations using a standardised way of doing things.

But even if you didn't subscribe to using that title of scientist, you'd still question what you observe.

For instance, if we look at this picture, you might think of a few questions.

For instance, what's actually causing that match to burn? Why is the flame that colour rather than perhaps red, or green, or even blue? And why does the smoke rise rather than fall? Now, to answer those kinds of questions, scientists conduct experiments, and once they decide which variables they're going to investigate, they write a method.

A method is essentially an organised plan of action.

It's step-by-step set of instructions describing how we're going to carry out an experiment.

Essentially, what it does is it takes those initial really disorganised and jumbled ideas and observations that we have and we put them into step-by-step instructions that people can follow to carry out that experiment or investigation.

Now, a good method will contain a variety of things.

First and foremost, that method will include the equipment that you are going to need in order to carry out that experiment.

Within that method as well, it's going to tell you how that equipment will be used.

Now, that could be either how to put the equipment together so how they'll be used in conjunction with each other, and it might also tell you how you're going to use that equipment to take any measurements throughout the experiment.

And finally, the way the method is written will be very concise.

It's gonna use clear language and these command words.

Now there are two main ways in which we can indicate what equipment will be used in a particular experiment.

The first is to simply list them, and usually you do that with bullet points.

The second way we could do this is using a labelled scientific diagram.

So looking at that equipment list, I could actually put them together to show how they'll be used together.

Now, which method you use to indicate which equipment you're going to be using in an experiment has both advantages and disadvantages.

So if we look at the equipment list, what I really like about having a bullet-point list is that I can actually tick them off as I go.

So I know that as I collect the equipment, I can just mark them as being collected and then move on.

But what this list doesn't do is tell me how I'm gonna be using this equipment together.

So if I'm unfamiliar with the equipment, I'm not sure how to put it together, I'm not gonna understand that from the list.

Now if we look at that scientific diagram, what it does do is show me exactly how I'm gonna put the equipment together.

I can see quite clearly that the tripod will be placed on top of the heat-proof mat, that the Bunsen burner goes under the tripod, and things like that.

But if I was to use it in the same way as my list and try and tick things off, that's really gonna muddle my diagram, and it's gonna make things a little bit trickier.

So either one is acceptable, and it's down to personal preference which way you're going to do that.

Now, regardless of which method you use to indicate the equipment that's needed for an experiment, what you need to remember to do is that anytime that equipment comes in different sizes, and any amounts of chemicals that you might be using should also be included in that equipment list.

So if we look at this bullet point list here, I can see that beakers are listed.

Now, beakers, if you remember, come in different sizes.

And I would like to indicate I need a 250-centimeter cubed beaker, not a 100-centimeter cubed beaker.

And also, I can see that a solution is being listed, but it hasn't told me how much.

So if I indicate actually I'm going to need 25 centimetres cubed, I'm gonna have to measure that out.

So I might actually need another piece of equipment.

A 25-centimeter cubed measuring cylinder will help make sure that I'm able to get the correct volume of solution going forward.

Now, if I was to indicate that using my scientific diagram, I could do the same thing simply by adding those sizes or volumes to the labels on my diagram.

So for my beaker, add 250 centimetres cubed, and for my solution, 25 centimetres cubed.

What I haven't done here is added the measuring cylinder, but that is something that you could also include in your labelled diagram as well.

Once I know what equipment I'm going to be using in my experiment, I'm going to look at my method in a little bit more detail.

Now that method is gonna use clear step-by-step instructions that's gonna tell me how I'm gonna use that equipment.

It's gonna tell me how to change the independent variable and what measurements I need to take so that I can keep track of the dependent variable as I go.

And it's gonna be doing this using very concise sentences.

It's gonna be in an easy-to-follow order, using clear language and those command words.

Now, command words are imperative verbs, and they indicate what you're going to be doing either with the equipment or in terms of the measurements that you're making.

So some of the more familiar command words that you might see in a method include things like stir, start, add, measure, record, repeat, pour.

There are things that you could shout out, "What do I do next?" "Stir." "What are you gonna do now?" "Measure." That's what we mean by imperative.

Now that we know the command words we want to use, what we need to do next is make sure that our instructions use concise language.

Now that means that the sentences that we use in our instructions are gonna be short and to the point.

So some examples that you might see include this.

"Measure three grammes of zinc powder using a balance.

Pour the acid into the conical flask.

Measure 25 centimetres cubed of acid using a measuring cylinder.

Start the stopwatch." You can see that all of these are very short, sharp sentences telling you exactly what to do using a few amount of words.

Let's look at an example method to show how all these good features have been brought together in these four short sentences.

So the first thing I can see here is that each of them are starting with a command word.

It also includes the measurements, the chemicals, and the equipment that's going to be used.

So even if I don't have a list of equipment or I don't have a scientific diagram that's been labelled, I can still find the equipment from these sentences.

These sentences as well are concise, using really short sentences that are kept to the point, and these steps are numbered so I can keep track, "Okay, I've done step one, now I need to go to step two." The good thing about this as well is, like before with our equipment list, you can tick off the steps as you go so you can keep track exactly where you are within that method.

Let's take a moment for a quick check to see how you're getting on.

Which one of the following is not a feature of a good method? Take a moment to pause the video so you can read through these.

Then come back when you're ready to check your answer.

Well done if you chose C.

Step-by-step instructions are not written as a paragraph, you're more likely to have them as bullet points or even better, as a numbered step-by-step list.

Let's move on to our first task.

What I'd like you to do is to read through the method and circle each command word as you find them in this method.

Pause the video and come back when you're ready to check your work.

Let's see how you got on.

Now if you remember, the command word is an imperative verb or phrase that tells us what we're going to do in each step.

So you should have circled the words crush, put, add, start, stir, stop, record, and repeat.

Now, what you'll notice is that the command words for these steps don't always come at the very start of our sentences.

And because of that, I would always recommend that you are reading a method first, fully, all the way through, before even collecting that first piece of equipment that you might need for your experiment.

In fact, my top tip for you is that when you are reading that method through for the very first time is to highlight those command words as you go, because that will make them stand out more when you're reading it later, for instance, when you're actually carrying out that particular experiment.

Now, for the second part of this task, you've been asked to peer review Aisha's method.

I'd like you to carefully read through it and then suggest at least five improvements to her equipment list and method combined.

So that's five total improvements between her equipment list and method.

Pause the video and come back when you're ready to check your work.

Let's see how you got on.

Now there are a variety of ways that you could have tackled this particular task.

And in fact, if you look through this suggested answers, and there are quite a few suggestions, you could have chosen any five of the highlighted changes to Aisha's method.

The way I would've tackled this is actually to read the method through first and then look at the equipment list.

Because we know that in our method, we need to be including command words, complete amounts of chemicals, all the equipment we're using.

It will tell us the size of the equipment we're using and how we're putting it all together.

And remember, we want our method to be concise but also specific.

So a good rule of thumb when you're reading through a method is, if I could give this to a nine or 10-year-old, would they be able to follow the instructions without getting confused? So these are the different changes you could have made.

You might wanna pause the video here and see if you managed to find of your five, match the ones that I've shown here.

Now, that wasn't an easy task for you guys to have a go at, but I hope you managed to find, if not five, at least three or four different changes that would've improved Aisha's method.

And extra points if you managed to include an amount of water and then also included that measuring cylinder and the stopwatch for recording the time, 'cause those were two pieces of equipment that was missing completely from her method and would've been a great thing to improve.

Well done.

Now that we're feeling comfortable looking at the features of a good method, let's move on to talk about repeatable versus reproducible.

When we're gathering results from an experiment, it's really important that we can be confident that they're as good as they can possibly be.

And the reason for that is because the results will become the evidence that we use to try and answer the question that we are investigating.

Now, there are a few ways that we can do this.

We can do that by making sure that we're choosing appropriate equipment and that we're using that equipment correctly.

We can make sure that our method that we're using is clear and that it's really easy to follow.

And finally, we can do is make sure that that method will help us to have repeatable and reproducible results to be collected.

So what's the difference between reproducible and repeatable? So a repeatable method is one in which the same person does the experiment in exactly the same way several times.

And when they do that, they are collecting same or similar results.

And you'll be able to see that by looking at their results table.

So we can see here that a tablet has been crushed roughly, and then the time has been measured to see how long it's taken to dissolve.

And they've done the same thing with a finely crushed tablet.

So if we look across each one of these rows, we can see that the results are coming up either exactly the same or very similar to each other.

What a repeatable method has then is a step that simply says, "Repeat the steps before so that you can record an additional result." So why do we want a repeatable method? Well, it allows for the easy comparison of results that have been collected by the same person.

You can easily compare one trial to the next of one person's set of results.

Now, if a method is repeatable, what that actually means is that the results that are collected are more likely to be reliable, and consequently then they're more likely to correctly answer the question the experiment is investigating.

Now, the way I remember that is repeatable results are reliable.

So you've got a little bit of alliteration there to help you remember the definition of repeatable.

So you might be wondering, "What's the big deal with being able to compare the results?" And the great thing about being able to compare results is that we can see whether or not one of our measurements was an accurate measurement or if it's just a random occurrence, if it was a fluke.

So by comparing these trials, we can see that there is one that doesn't fit.

Trial one is significantly different to the results that were gathered for trials two and three.

And if we had stopped at just trial one, our answers would've been very far from accurate.

So by being able to compare these results, we can find that our average is a little bit better.

And it might also indicate to us that maybe the equipment wasn't used properly in the first trial, or maybe the method wasn't properly followed in the first trial either.

The important thing, though, no matter what, is if you find an inconsistent result when you're comparing them, is that you completely ignore it when you're calculating the average.

If you have time, it would be recommended that you try and repeat and replace that inconsistent result, but only do that if you have the time.

Now, a reproducible method, on the other hand, is one in which different people are following the same procedure, so the same method, and they're able to achieve same or similar results as the other person.

So here we have Sophia and Jun both doing the same experiment, and we can see here that their results for the roughly crushed tablet were fairly similar, and the same can be said for their finely crushed tablet.

So one thing we can also say about a reproducible method is that whilst they're done by different people, they could possibly used slightly different equipment.

They may have altered the method also slightly based on what they have available, but they're still achieving similar results.

Now, you might be wondering, "What's the big deal about trying to have a reproducible method? If it's already repeatable, why should we go through the hassle of having somebody else carry out this method as well?" Well, when it's reproducible and you're able to compare the results between different people, what you're doing is gathering strength for the evidence that you've collected.

It's ensuring that your results are reliable and, more than that, that they're trustworthy.

It's essentially a way of having your results peer reviewed so that there's even more confidence in the evidence that you've gathered to try and answer the question of an experiment.

Let's stop for a quick check to see how you're getting on.

True or false? A repeatable method is one in which different people record similar results using the same method.

Well done if you chose false.

But what's the reason why? Is it because a repeatable method is one in which the same person follows the same method and obtains similar results? Or is it that a repeatable method is one in which different people record similar results using different methods? Pause the video and come back when you're ready to check your answer.

Well done if you said A.

A repeatable method is one in which the same person follows the same method and obtains similar results.

Good job, guys.

Let's move on to the last task of today's lesson.

For this first part, what I'd like you to do is to read through each of the statements and decide if it's describing a repeatable method or a reproducible method.

So pause the video here and come back when you're ready to check your answers.

Okay, let's see how you got on.

So for part A, you should have said that it was repeatable.

So even though we have two students working here, Sam and Laura, they've worked together as a team to collect one set of results.

So that makes it repeatable.

For part B, we've got Andeep, who has timed a reaction, and then Izzy, a different person who's used his method and obtained another answer.

So because we've got two different people using a similar method, it's reproducible.

In part C, we've got Lucas and Jacob, who have independently measured the distance a paper aeroplane flew, and they've used somebody else's method.

Then we have two different sets of results.

As a result of this, we can say that this is reproducible 'cause we have multiple people using a similar method that is being checked.

Okay, for part two of this last task, we want to look at a method that Alex has written to find out if the volume of solvent used will affect how quickly a solute dissolves.

So his method will be shown in a moment, but what I'd like you to do is help him to rewrite it by including features of a good method.

And I'd like you to try and take care to include details that will help it to be both repeatable and reproducible.

Here's his method, try to change it into a better method, and pause the video, and come back when you're ready to check your work.

Let's see how you got on.

Now, there were a lot of different ways that you could have improved Alex's method.

The two easiest things to do would've been to take his paragraph method and turned it into numbered step-by-step instructions.

This helps to keep the sentences concise and easy to identify one step to the next.

The other was to create a separate equipment list and including the volumes, and sizes, and things like that.

Now, I asked you to take care to ensure that the method was both repeatable and reproducible, and that would've been by including extra steps.

So if you look at steps eight and nine, that is making the method repeatable because you're asking the person who is following this method to repeat what they've already done to make it more reliable.

In step 10, that is what actually makes it reproducible, by comparing your results with somebody else who's done it.

Well done on a tricky task, it can be a little time-consuming if you let it be.

So what I would suggest you do when you're looking at methods is maybe have a strategy on how you want to improve things.

First of all, make a paragraph into step-by-step instructions.

Secondly, make sure you've got your command words and that those sentences are concise, and straightforward, and clear to follow.

And then, finally, I would include my equipment list.

Well done, though, guys, on what is a difficult task.

Good job.

So let's finish up by just summarising what we've learned in today's lesson.

We've learned that a method is a step-by-step set of instructions on how to carry out an experiment.

And a good method has many features, including a detailed list or a labelled scientific diagram.

And that method will include concise sentences using clear language and those command words.

And we also learned that a method should be written so that it's repeatable, so that's the same person repeatedly using the same method and getting similar results.

And if we can, try and make that method so that it can be reproducible, so that's other people using a similar or the same method and also achieving similar results.

I hope that you've enjoyed learning with me today.

I've certainly enjoyed having you with me, and I hope to see you again soon.

Bye for now.