Lesson video

Hello, everybody.

It is Miss Simkin back again for your next science lesson.

I hope that you have been keeping well since our last lesson.

I have something exciting to show you.

I don't know if you'll be quite as excited as I am about this, because when I saw this this morning, I was very, very, very excited, especially considering how small it is.

But do you remember that I showed you the plants that I planted last week? Well, one of them has started to germinate, and you can barely see it.

It's so tiny.

I did warn you.

But I'm going to bring it up to the camera.

Can you see the first little tiny plant coming through? Unfortunately, nothing's happened in this one.

It's all by itself.

But maybe next week or next time I record a lesson, there'll be something else to show you.

But that really brightened my day when I saw it, and I hope that there's been something to brighten your day today.

If not yet, then hopefully something in this science lesson will get you as excited as I was about my teeny tiny forget-me-not that's growing.

Let's get started.

Now for today's lesson, you are going to need these four things.

You're going to need a piece of paper or an exercise book, a pencil, a colouring pencil if you would like to mark your work in a different colour, and a ruler.

You're also going to need these star words.

So let's practise saying them together.

And then the one that's underlined, we're going to learn now or revise because we've actually already learned the word species before, and then we're going to learn what the other words mean in our lesson.

So our first word is geologist.

I'm going to say it and then you're going to say it.

Geologist! Great, geological era.

Mass extinction.

Extinction and species.

So a species is a group of organisms with similar characteristics that can breed together.

So for example, a human is a species or a giraffe is a species.

All giraffes have similar characteristics to each other and they can breed together.

But remember, they can be plants as well as animals.

This is the structure our lesson is going to take today.

So we're going to start with some recap like we always do, then we're going to learn about extinction, then we're going to learn what a geologist is, we're going to look at geological eras, and then we're going to look at the organisms found in each era.

So let's start with our recap.

Can you remember what variation is now? This is lesson number four, and we have looked at this word every lesson.

So I want you to have a go at seeing if you can remember what it means.

The picture's there as a prompt.

I'm going to give you a hint.

All of the puppies are a little bit different.

So do you know what variation means? If you do, say it to your screen.

Variation is? Variation is the differences between organisms. Well done if you got that correct.

Can you remember what an adaptation is? You've got the picture there as a prompt.

If you know it, say it to your screen.

An adaptation is? A characteristic that helps an organism to survive in its environment.

Well done if you remember that.

So that picture is to remind you that some of Darwin's finches had different size beaks.

That was their adaptation, okay? Evolution, can you remember our definition for evolution? It's very gradual.

That's your hint.

If you know it, say it to your screen.

Evolution is the process by which living things gradually change over time.

And we looked at this in our very first lesson.

Evolution occurs because there's variation between different species, so they're all slightly different.

So for example, they might have different shaped beaks.

There will be some beaks or some adaptations that mean an organism is better adapted to its environment.

That means it's more likely to survive.

If an organism is more likely to survive, it's more likely to reproduce and have offspring.

And then eventually over time, over thousands and hundreds of thousands and millions of years, that species that's best, sorry, that organism that's best adapted will have lots, and lots, and lots of offspring, and the organism that's not very well adapted, it won't survive.

And so we'll only be left with the well-adapted beak in this example.

Okay, and if we give it enough time, a whole new species might evolve.

We've also looked at the fossil record.

Can you remember what the fossil record is? The fossil record is a collection of fossils found across different ages of rock, which we use as evidence for something.

What do we use them as evidence for? If you know it, tell it to your screen.

We use them as evidence for evolution, great.

And then last lesson, we looked at the animal kingdom.

So the animal kingdom is split into two sections.

It's split into invertebrates and vertebrates.

Can you remember which ones had a spine, which ones had a backbone? If you know it say it to your screen.

Great, vertebrates have a backbone, and you can feel yours in your back.

Vertebrates are then split into five different groups.

If you can remember what those five groups are, then pause the video and write them down on your piece of paper now.

Great, let's check if you are correct.

Number one is fish.

Number two is amphibians.

Remember that sound is a PH.

Check your spelling for me.

Number three is reptiles.

Number four is birds.

And number five is mammals, like us.

Well done if you remembered those.

So, as I said, today, we are going to find out when these different groups of animals evolved.

Let's start with extinction.

This is the first part of our lesson.

To explain to you what extinction is, I'm going to talk about dinosaurs.

This is a picture of a dinosaur, and I know that lots of you will know lots about dinosaurs, maybe even more than me.

Dinosaurs are no longer alive.

They no longer exist on our planet.

We know that because although we might read about them in our science books or maybe storybooks when we were younger, none of you has ever walked down the street and bumped into a dinosaur.

Sadly, they no longer exist on our planet.

Extinction of a species takes place when there are no longer any members of the species alive.

So dinosaurs are now extinct because none of them are alive anymore.

So although it's often thought that extinctions are rare and dramatic events, the fact is that many, many species have become extinct over the history of the Earth.

So it's not just our dinosaur friends who are now extinct, but over the history of the Earth, lots and lots of animal groups and species have become extinct.

An organism can become extinct for a number of reasons.

So for example, there might be new predators in the area that hunt our organism.

It might be that other animals may take the food that our species requires.

So if this dinosaur was competing for a particular type of leaf or plant with another species, then it could become extinct if the other species is better at getting that food and takes it all.

It might be because the climate gets too hot or too cold, or it might be because new diseases start to spread.

So these are the main four reasons: new predators, competition for food, climate change or diseases.

Those are the four main reasons why a species might go extinct.

Sometimes on a very rare occasion during the history of earth, we might have something called a mass extinction event.

What's it called? A mass extinction event.

This is when a dramatic event, such as a huge volcano exploding or a large asteroid hitting the earth, can cause the extinction of most of the life on earth.

So in a mass extinction event, it's not just one species that goes extinct.

It's lots of species.

Most of life that's there on earth at that time goes extinct, and this is what we believe happened to the dinosaurs.

So we believe that the dinosaurs went extinct because of a mass extinction event.

So here is recap of our definition of extinction.

It takes place when there are no longer any members of a species alive.

Here are some questions for you to answer on extinction.

What is extinction? Give three reasons why extinction may take place.

What are mass extinction events? And which group of reptiles do we think may have been made extinct by a mass extinction event? You can pause the video and complete those questions now.

Great, let's see if you got those answers correct.

So the first question was, what is extinction? And the answer was extinction of a species takes place when there are no longer any members of the species alive.

Give yourself a tick if you got that correct.

If you need to edit your answer, that's okay.

Use a different colour to do that now.

The second question asked for three reasons.

So if you had any three of these, you can give yourself a tick.

If not, just add them in.

So new predators, disease, climate change, or competition for food.

Well done if you got those correct.

Our third question asked, what is a mass extinction event? So your answer for this might have been, this is when a dramatic event such as a huge volcano exploding or a large asteroid hitting the earth can cause the extinction of most of the life on earth.

Give yourself a tick if you got that.

The key point there is extinction of most of life on earth.

Okay, so if you don't have the examples of the asteroid and volcano, that's okay, but make sure you have that key point.

Mass extinction means most of the life on earth, okay? You can even underline that to show that it's the most important part of your answer.

If you don't have it, that's okay.

Pause the video and add it in.

Most important, sorry, not most important, most of life on earth.

Question four asked what reptiles do we believe suffered a mass extinction event? And the answer is dinosaurs.

Dinosaurs were a type of reptile.

Well done if you got those correct.

That brings us to our next section, which is all about geologists.

Have a look at these pictures on the screen.

I'm going to give you 45 seconds to look carefully at the pictures, and I want you to see if you can work out what a geologists does.

So these are all pictures of geologists.

What do you think a geologist does? 45 seconds, have a look.

You could even make some notes on your piece of paper if you wanted to.

Great, so I'm now going to tell you, and you can see if you guessed correctly.

Geologists are scientists that study rocks.

So you can see in all of those pictures, there are rocks, and they study those rocks so that they can understand things about the world.

You can see from the pictures on the board, that geologists do lots of different things in their job.

So sometimes they might have to work in the field, collecting rock samples or studying rock samples.

Sometimes they might play a part in educating other scientists or other people.

So you can see that one of the scientists is actually giving a talk to some people on a tour about the rocks.

Sometimes geologists have to go into quite adventurous places in order to find rocks.

So you can see one of them is being very brave and studying the rocks inside a cave.

And sometimes they need to study their rocks back in a lab.

So they might take samples and then do lots of tests on the rocks back in the lab.

Geologists have found out from their studies of rocks from different periods of time that there have been a number of mass extinction events.

So it's geologist who discovered that mass extinction events, like what happened to the dinosaurs, occurred, and it's geologists who tell us when those mass extinction events occurred.

So they have also given a name to something that's the period of time between two mass extinction events.

So these periods of time between two mass extinction events are called geological eras.

And if we study the fossils that existed during each of those eras, we can find out what type of living things might have been alive during that period of time, and this helps us to see how life has changed across each era and how life has changed over the history of the earth.

So geologists have to work quite closely with another type of scientist that we studied called palaeontologists.

So geologists study the rocks, and palaeontologists study the fossils, and together they can give us a really good picture of how organisms have changed over periods of time.

So all of the things we're going to learn about this lesson, we wouldn't know if it weren't for the discovery of some really fantastic geologists and palaeontologists.

So let's talk a little bit more about what a geological era is.

So a geological era is the period of time between two mass extinction events.

So if we have the mass extinction event, for example, of the dinosaurs, that's one period.

That happens at one point in time.

Then time goes on, and on, and on until another mass extinction event occurs, maybe this time of a different species of animal.

The time between those two we called a geological era.

Okay? So say the definition with me to help us remember.

Geological eras are periods of time between extinction events.

One more time.

Geological eras are periods of time between extinction events.

Great.

Can you have a go now please at answering these questions? Number one, what does a geologist do? Number two, what are geological eras? Number three, what can we find out from the fossils about each geological era? Pause the video and complete those questions for me now please.

Great, let's check our answers.

So number one, geologists are scientists that study rocks to understand things about the world.

Well done if you got that correct.

Give yourself a tick.

Number two, geological eras are periods of time between extinction events.

Well done if you got that correct.

Number three, you might have written an answer like this.

Don't worry if your wording is different to mine.

As long as you've got the main ideas down, you can give yourself a tick.

So if we study the fossils that existed during each geological era, we can find out which types of living things would have lived during each period of time.

You also might have written something about understanding the history of living organisms or how living organisms have changed over time.

Okay, let's look a little bit more closely at different geological eras.

So it's believed that the earth is 4.

5 billion years old, but life didn't begin on earth until only 3,600 million years ago.

I say only, that is a really, really long time ago.

So the first life on earth was 3,600 million years ago, but that was still a very long time after the earth was first created.

From what we have in the fossil records, we know that life has changed a lot since it first began millions of years ago.

And with each mass extinction event, we have new types of life and new groups of living organisms that have come into existence.

So we're going to start by learning what the four main geological eras of time are, okay? So all of these are quite long words that are fun to say.

So we're going to say them a couple of times to practise them and to learn them.

Okay, we're going to start with the first era.

So our first era that we're going to learn about happened 3,600 million years ago.

So you can see on my timeline, we're going to start at 3,600 million years ago.

Now, I've only written the number 3,600.

That's because it would take up a lot of room on my timeline to write 3,600 million.

I need to add another six zeros to that number on the screen.

So you can see in the top right-hand corner, I've got a little key that says timeline shows million years ago.

So any number on my timeline, you need to add a million to.

So it's not 3,600 years ago.

It's 3,600 million years ago.

Okay, and we learnt already that that's when life first evolved.

So that's our starting point, okay, of our first era.

And the first era is called the Proterozoic era.

Proterozoic era, practise saying it with me.

Proterozoic era, Proterozoic era.

Your turn, great.

Now I sometimes remember that Proterozoic era becomes first because it starts with pro and I think the first life on earth, well, those organisms must have been pros.

It's a bit of a silly way, but that helps me remember.

Okay, so the Proterozoic era is first.

Our next era starts 530 million years ago, and that's called the Paleozoic era.

Let's practise saying it, Paleozoic era, Paleozoic era.

Great, and we're going to learn in our next section about the kind of organisms that were alive in this era.

Then 230 million years ago, we have the Mesozoic era, Mesozoic, Mesozoic.

And then the last era that we're going to learn about started 66.

4 million years ago, and it's called the Cenozoic era, Cenozoic era, great.

Now, I'm going to tell you lots of information about what happens in each of those eras, but before we start, I would like you to just get your page set up for this lesson so that as I'm speaking and as I'm teaching, you can make notes as we go.

So what I would like you to do now is to pause the video and to draw this table onto your piece of paper or onto or into your book.

I would suggest using a whole, nearly a whole page for this.

So if you just have a little bit of writing so far, that's fine, but if you've already made quite a few notes, I would start a new page for this table.

Okay, and for each of the eras in the column, so Proterozoic, Paleozoic, Mesozoic, and Cenozoic, you're going to need more than one line.

You're probably going to need about four lines for each depending on how detailed you want your notes to be.

Okay, so I'm now going to make it full screen so you can see really clearly, and I'm going to ask you to pause the video and copy this and remember to use a ruler, please.

So far, all the work I've been seeing has been so neat.

Good job.

So pause the video and copy this in now, please.

Great, so now we're going to talk about the organisms found in each era, and you're going to make some notes as we go.

So you've got two columns, one to write how many million years ago and the other is to write what happened, so what organisms were alive there and any notes that you take, either you want to take about the eras while I'm teaching.

Okay, so we've already learned, our first era is known as the Proterozoic era.

So we're going to be making notes in the Proterozoic section of our table.

But within each era, we're going to look at a couple different dates.

So the first date you can write down is 3,600.

You don't have to write all those eras for million 'cause it says at the top of your column million years ago.

So you can just write 3,600, and this is when life first began.

The first life on earth were very, very, very tiny organisms, so micro organisms that were like bacteria.

And for a long time, this was the only type of life that existed until 2,100 million years ago.

So that's the next bit on our timeline.

And this is when we had our very first, simple, small plants called algae.

All life existed.

All the life that existed at this point was in the earth's oceans, and algae, which were the very first tiny, simple parts, started turning carbon dioxide into oxygen.

So recap, 3,600 million years ago, bacteria was the first life on earth.

2,100 million years ago, we had algae, which is, we still have algae around today.

It's like the green plants that you might find covering rocks or on the top of ponds, but this would be different to the kind of algae that first evolved a long time ago.

So this is roughly what your notes in your table should look like.

So you should have two bullet points for each of those times.

So 3,600 million years ago and 2,100, and then at least one bullet point for each of those.

So bacteria first evolved.

It says green first evolved.

That should say green algae evolved.

And then I've added an extra note, all life existed in the oceans.

You might have even more detail than me and that's great, well done, but this is the minimum of what you need.

Okay, so you can take this opportunity now to tick if you've already filled in your table for this first section.

If not, then you've got an example on the screen that you can use to fill it in now.

So pause the video if you need to at this point.

Okay, so our next era that we're going to learn about is the Paleozoic era.

So this is the second era, and it began 5,003, sorry, I just read that number wrong.

It began 530 million years ago.

Now this is the point when many kingdoms and types of animals began to appear, and we actually call this point at 530 million years ago, we call it the Cambrian explosion.

Now, the reason we call it that is not because there was a big explosion on earth at that point but because so many animal numbers started to appear at that point, and new animals started to appear that it was almost like an explosion of animals.

Okay, so we call it the Cambrian explosion.

And we know that so many animals started to appear at this point because the fossil record shows us that.

There are loads of fossils from this time.

The first fish also appeared at this time in the Cambrian explosion, and then 420 million years ago, that's when the first plants appeared on land.

So we had our first pants on land.

So before, we'd only had algae and plants in the sea, and then 420 million years ago, we get our first plants on land.

Then 370 million years ago, that's when our first amphibians evolved.

So that's one of our animal groups that we learned about last year.

So amphibians evolved 317 million years ago.

Now, these pictures that I'm showing you are to help you remember, but we wouldn't have had photos of amphibians from those times.

So you'll have to use your imagination a little bit.

Amphibians have evolved.

They've changed lots in 370 million years ago.

Our next group of animals to appear appeared 340 million years ago, and that group was reptiles.

So we had our first reptiles 340 million years ago.

In a moment, I'm going to go onto the next slide and talk about the next era.

So if you need some more time to take your notes down, then pause the video and complete your notes about the Paleozoic era now.

Great, when you're ready, we'll move on to our next era.

Our next era is the Mesozoic era, and this began 230 million years ago.

This is when the mammals first evolved.

So we had our first mammals 230 million years ago.

Now, I always remember that mammals evolved in the Mesozoic era because they both begin with M.

Okay, so that's my sticky way of remembering.

When did mammals evolve, which era? Tell your screen, the Mesozoic era.

This is also the period of time that dinosaurs existed.

So throughout the whole Mesozoic era, dinosaurs existed.

The first birds appeared 190 million years ago, and then our first flowering plants appeared 141 million years ago.

So we had plants before this, but they didn't start flowering until 141 million years ago.

Oh, sorry, I should've said before I moved on.

I'm going to move on to the next era now.

So if you need a little bit more time to make notes on this section, then just pause the video and do that now before we move on.

Great, our next era is the Cenozoic era.

This started 66.

4 million years ago when dinosaurs became extinct sadly.

So it's believed that at this point 66.

4 million years ago, all the dinosaurs seem to have died at one time, and it's believed that a giant rock from space hit the earth and this caused all the dinosaurs to be killed.

However, we're not 100% sure what happened, and there are some different ideas about that.

So the fossil record and studying rocks can tell us lots about what life used to be like on earth but doesn't tell us everything.

Sometimes it just gives us clues, and we need to try and find the answer.

So this is the fourth and final era because we're still in the Cenozoic era today.

So the Cenozoic era is still going on.

2020, where we are now, is in the Cenozoic era.

And from this point onwards, all living creatures that are around today have evolved.

So 2.

5 million years ago, we got the first human-like animals, so the first organisms that started to be a bit similar to humans.

And then 0.

2 million years ago is when we think modern humans first evolved.

So that's when we find the first fossils for them and modern humans are humans who are similar to us.

We are modern humans, okay? So in the grand scheme of things, 0.

2 million years compared to how long life has been on earth is not very long, but 0.

2 million years ago feels like a very long time for us 'cause it's much longer than our lifetime, and that's how long humans have been on the planet.

So we're going, sorry, again, I should have said.

I'm too excited to go into the next part of the lesson.

If you need some more time to make your notes, then pause the video and do that now.

Great, now we're going to mark our tables and see if you got the same as me.

So for the Paleozoic, we had four main times, and that was 530 million years ago when the Cambrian explosion occurred, 430, when the first plants evolved, 370, when the first amphibians evolved, and 340 million years ago, when the first reptiles evolved.

So give yourself a tick if you got those.

If you missed any of them, just add them in for me, please, because those are our key bullet points.

If you wrote more notes and more detailed notes than me, then great job, well done.

If you need more time, pause the video before we move on to the next section.

Great, the next section was our Mesozoic.

So our three main points on our timeline were 230 million years ago, the first mammals evolved, 190 million years ago for the first birds, and 141 for the first plants.

Give yourself a tick if you got those right.

Add them in if you need to and well done if you got some extra notes down.

And now, the last era, the Cenozoic era.

So 66.

4 million years ago, the dinosaurs go extinct, 2.

5 million years ago, the first human-like animals evolve, and then 0.

2 million years ago, modern-day humans evolve.

So give yourself a tick if you got those right.

Add them in if you need to and well done if you got some extra details down while I was teaching.

Great, so that brings us to the end of today's lesson, but I have a suggestion of a task that you might like to do.

This is completely optional and up to you, but something that might be nice to do is to take the detail that you've put in your table and actually draw it into a timeline.

So I showed you lots of pieces of timelines as we were going through the lesson.

You could make one big one with all of the key events that happened.

And if you wanted to, if you like drawing, then maybe you could even draw a picture underneath each one.

So you could draw a picture of a mammal after first mammals evolve.

Have a lovely, lovely day, everybody, and I will see you back for our next lesson.