Hello, scientists.

My name is Mr. Wilshire.

In this lesson, we're going to be looking at what plants need.

This is the do stage.

The outcome for this lesson is I can set up a comparative test investigation to find out what plants need.

There are some keywords for us to consider as we work our way through this lesson.

The first is plant, then it's comparative test, after that is variable, and finally, record.

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

The definitions have appeared on the screen for you now, so if you need to, you can pause a video now and have a quick recap about what they mean.

Pause the video now if you need to do that.

Restart when you're ready.

The first part of this session is called setting up a comparative test investigation.

Alex and his class are investigating the needs of plants.

There you can see some plants.

There's lots of green leaves, there's flowers there, and all sorts.

Looks like a lovely summer's day.

They're going to remove requirements from some plants and observe what happens to them.

So have a think here.

What are the things that plants require to grow and be healthy? Have a think.

Restart the video when you've done that.

What did you think of? What are the types of things that plants need? What do they require to grow and be healthy? Let's find out.

Plants need air, water, light, room to grow, nutrients from the soil, warmth.

Anything else that we might have forgotten? All of those things are very important.

If there's no air, the plant can't breathe.

If there's no water, it can't grow.

If there's no light, it won't be able to photosynthesize, will it? If there's no room to grow, there's nowhere for the roots, so it'll just stay the same size.

If there's no soil to give it nutrients, there's no food for the plant.

And it needs to be warm as well because plants don't grow especially well during the winter.

Stop and think.

We can investigate what plants need by observing plant growth when we time how long it takes them to grow, we take away one of their requirements, or we compare their seeds.

Which one of these statements best fits this question? The correct answer here is we take away one of their requirements.

We can use a comparative test investigation to find out more about the requirements of plants.

In this comparative test investigation, we're going to change one variable, we're going to measure another, and we're going to keep all the other variables the same.

Alex says, "Well, I've planned a comparative test investigation to find out what happens when a plant doesn't have water." That's a good idea.

That's one way of testing to see if plants really do require a lot of water to grow.

If you remove the water, then how is it going to grow? Alex says, "I'm going to put a plant in soil and leave it in a sunny place so it gets light and air.

It'll also be in a pot that gives it plenty of space to grow." Hmm, I wonder if Alex has forgotten anything here? Jun says, "How will you know if not having any water has made a difference to the plant?" What do you think? How is Alex going to measure this? Pause the video here and discuss.

Restart when you've done that.

So what did you think? How is Alex going to measure success here? Alex will need to grow two plants so that he can compare the difference between a plant with water and a plant with no water.

There you can see a picture of Alex's comparative test investigation.

Two pots, and one of them says, "water," and one of them says, "no water." Alex will keep all the other variables the same.

He's going to label his plants so he knows which is which.

It's a good idea to label things otherwise you might forget.

Alex then says, "I'll give each plant the same amount of light, air, and room to grow.

I'll give the the same type and number of tablespoons of soil so that they will have access to the same amount of nutrients from the soil.

They'll be kept at the same temperature as well.

I will give one plant water and the other plant will get no water.

This will let me see the effect of having no water compared to having water on the health of the plant." So Alex really has thought about every step of his investigation, hasn't he? He's got his one plant that he's gonna change a variable, and he's got his control plant as well.

Something for him to measure against.

By giving one plant all of the things that it needs, it's going to be able to grow.

Whereas the other plant, we think it might not grow.

But your prediction might be different to Alex's here.

Stop and think.

Alex will grow two plants in his comparative test investigation so that he can compare the plant grown with water to the plant grown without water, he can have more tries at growing plants, or his tables will have more results in.

What do you think is the best way to answer this? Restart the video when you've done that.

The correct answer here is a, so he can compare the plant grown with water to the plant grown without water.

Laura has planned a comparative test to investigate this question.

How does having no nutrients from soil affect plant growth? She says, "I'm gonna put both of my plants in the same place.

I'm going to grow one plant in soil and give it water.

I will grow my other plant in sand and give it no water." What do you think about Laura's plan here? Does it make sense? Discuss.

So what's Laura's plan like? Has she forgotten anything? What did you think of? Jacob says, "You need to keep all of the variables the same except for the one that you you're investigating.

That will help you to see what effect the nutrients from soil have on your plant." So she says, "Okay, I'll give both of my plants the same amount of light, space, and water.

I will only change the soil." Hmm, that seems much better.

She's only changing one thing now.

Stop and think.

Lucas is investigating this question.

How does having no light affect how a plant grows? What's the variable that Lucas will change in his investigation? Is it the volume of water, the type of soil, or the amount of light? The correct answer here is the amount of light.

The variable that Lucas will change in his investigation is the amount of light.

This brings us nicely onto the very first task.

You need to set up your own comparative test investigation into plant requirements on plant health.

You can use your own plan or Laura's plan that's on the next slides.

So set up two plants, one which has all the requirements, and another which will have one requirement taken away.

Make sure that you keep all the variables the same across both of your plants, except for the one that you're investigating.

So it's up to you here.

You can decide to come up with your own plan, or you can use Laura's that I'll show you in a moment.

You decide.

Here's Laura's plan.

"The variable I'm changing," she says, "is nutrients from soil." So step one, get two plant pots and label one soil and the other no soil.

Step two, use tablespoons to add an equal amount of sand to the no soil pot and soil to the soil pot.

Step three, dig a small hole and gently place a small plant in the centre of each pot and press it just below the surface of the sand or the soil.

Step four, use the tablespoon to give each plant an equal amount of water.

Step five, place both pots in a place where they will get the same brightness of light and be kept at the same temperature.

Here is Laura's fair test investigation.

One with soil and one with no soil.

I wonder which plant is going to grow best? Good luck with your experiment.

Restart the video when you've done that.

How did you get on? Well, your experiments may have come up similar to these.

Andeep says, "We're investigating how not having light effects a plant, so I'm keeping all the variables the same except for the brightness of light the plant will get.

I put both plants on the windowsill in the classroom, but I will cover one with a cardboard box." And Sam says, "Well, the variable we're going to change is the brightness of light.

We're going to keep the same the amount of soil, water, temperature, and the size of the pot." So those are two different ideas there, or maybe you used Laura's ideas in your plan.

However you decided to complete your task, I'm sure you are able to think about the different variables.

Well done.

The second part of this lesson is monitoring changes over time.

In a comparative test investigation, one thing is changed and another is measured.

So Alex here is investigating the effect of not having water on plants.

The variable that he is changing is the water, isn't it? So in this case, what is Alex going to measure? Hmm? Have a think and discuss.

Restart the video when you've done that.

So what's Alex going to measure here? Let's find out.

Alex wants to measure the health of his plants.

So if he's measuring the health of his plants, what does that mean? What observations could he make? Discuss.

How can you measure plant health? Well, Sophia says, "I think results from investigations always have to be numbers.

He could count the number of leaves on his plants or measure the height of each one." And Laura says, "I think it will have to be words.

I don't think you can measure health with a number." What do you think? Is there a way of measuring health with a number? Discuss.

Alex could choose to measure his plants in many different ways to see what effect not having water has had.

So he could observe the height of the plants, the number of leaves, colour of the plants, or the overall appearance of the plants.

He says, "Did you think of anything else?" There's lots of different ways that you could measure their health in this case then, isn't there? I wonder if you thought of anything new.

When scientists carry out inquiries, they plan when they're going to need to make their observations and how they will record them.

Here's Alex again, and he says, "I'm going to observe my plants every morning for the next three days." What do you think of Alex's idea here? Is this a good way to conduct his experiment? Hmm? I wonder.

Just observing every morning for the next three days, is that going to be enough? Let's find out more.

Plants do take quite a long time to grow and change, don't they, so Alex will want to make observations over a number of days or weeks.

I don't think he's going to see an immediate result, is he? He may need to wait until the following week.

He says, "I think it would be better to make observations every five days for the next three weeks." That's a slightly better idea, isn't it? He could monitor each of the plants every five days instead, just to be sure.

But if you really wanted to be sure, you could take a photograph every single day, couldn't you, and then compare each of those photographs at the very end.

Let's stop and think.

Which would be the best schedule for observing changes to plant growth over time? Is it every three minutes, every three hours, or every three days? The correct answer here is every three days.

Scientists also plan how they're going to record their observations.

They could use some photographs.

Oh, I said that one earlier, didn't I? Some diagrams, tables, writing.

How could we record our observations of the plants in our investigation? Are we just going to take photos, or do you think that we need to add anything else? Discuss.

So what else do we need to add? How could we record our results here? Alex has decided to draw a diagram of his plant and then label it every three days.

Andeep says, "I'm going to keep a plant diary and write about the height of the plant and how it looks once every week." Oh, he's going to need a ruler to complete that task, isn't he? So two different ideas there.

I wonder which you're going to choose.

Stop and think.

Which of these recording methods would not be good for keeping observations of plant growth over time? A photograph of the equipment used for the investigation, a table showing the height of the plants at the end of each week, or a diary of changes every few days.

The correct answer here is a photograph of the equipment used in the investigation.

That's just taking a photo of the equipment, isn't it? It's not actually recording anything to do with the experiment.

Here is Task B.

You need to make a plan for recording observations of your plants.

Decide what you're going to need, decide what you're going to record, how you're going to record it, and how often you'll need to make your observations.

Remember, each person's investigation idea is going to be different, so it will need a slightly different way to record, won't it? So best of luck with making a plan to record your observations.

Restart the video when you've done that.

How did you get on? Here's Aisha's idea.

See if yours was similar.

"I'm going to take pictures every five days and keep a photo diary.

I'm going to add a note at the bottom of each page to describe the appearance of the plants and show how tall the plants are in centimetres." What a great idea.

So using some images and using some writing as well.

She's also measuring each time too, so she's got a mixture of different ideas there.

Remember, it doesn't just have to be one, does it? Jacob says, "I've made a table to record the height of each plant and the number of leaves it has at the end of each week." So one row is there about the height, and the other row is there about the number of leaves.

Again, another really good way to record all of this information.

I wonder how you decided to record your observations here.

Let's summarise our lesson.

Scientists can investigate what plants need by observing plant growth when requirements are removed.

In a comparative test investigation, we compare differences.

We keep all variables the same for both plants except for the variable that we're investigating.

To keep track of how things change over time, we can set up a plan for when to make observations and how to record them.

Hopefully you've been inspired to make some observations of your own.

I wonder how you're going to record your observations though.

You could use a camera or maybe use some of your creative drawing skills.

Well done for completing your tasks.

I've been Mr. Wilshire.

Thank you very much for listening.