Lesson video

Hi, I'm Miss Mia, and I'm really looking forward to teaching you this lesson today.

In this lesson, you'll be able to use a light microscope to observe cells.

Your keywords are on the screen now.

You can write them down or repeat them after me.

Cell.

Lens.

Light microscope.

Focus.

Magnification.

Great.

Let's find out what these keywords mean.

A cell is the smallest living building block of a living organism.

A lens is a piece of curved glass, which focuses light to alter the size of an image.

A light microscope is a piece of equipment that uses to focus light and enlarge the object's image.

Adjusting the focus of a lens makes an image clearer.

Increasing the magnification of an object makes it look bigger.

Super.

Let's move on.

So this lesson is all about observing cells with a light microscope.

So this lesson has three lesson cycles.

Our first lesson cycle is all about living organisms and how they are made up of cells.

Then, we'll be looking at how microscopes are used to view cells.

And lastly, we'll be using a microscope.

I'm super excited about this lesson.

I hope you are too.

Let's get started.

All living organisms are made of living building blocks.

These living building blocks are called cells.

Cells are usually far too small for us to see unaided.

We have to magnify them to see them.

Here's a picture of an animal, magnified view of cells that make up the animal's heart.

In humans, other animals and plants, groups of similar cells work together in tissues.

Groups of tissues working together to perform a certain function are called organs.

So here we can see groups of cells.

They form a tissue.

All our tissues, for example, muscles and bones and all our organs, example, heart and skin are made of cells.

Here we have a photo of a plant, cells that make up the plants leaves.

And here's one plant cell.

Cells are living because they carry out all the common processes of living organisms.

Which of these common processes can you remember?

Have a think.

You may remember MRS.

GREN.

So each letter stands for a life process, M for movement, all living things can move, even plants move slowly.

R for respiration, releasing energy from food.

S for sensitivity, responding to changes in the environment.

G for growth, getting bigger or developing.

R for reproduction, making more of the same kind.

E for excretion, getting rid of waste.

And N for nutrition, taking in food or nutrients.

Because cells can do all of these, they are considered living.

Over to you, which statement about living organisms is true?

Is it A, a living organism contains cells?

B, a living organism is made up of cells?

Or C, there are no cells in a living organism?

What do you think?

You can pause the video here and click Play when you've got the answer.

So what did you get?

If you got B, you're correct.

A living organism is made up of cells.

So remember, cells are the basic building blocks of life.

Just like a house is made from bricks, all living things are made from cells.

In organisms, cells form tissues, tissues form organs, organs form organ systems.

And then organ systems form the whole organism.

So if something is living, it must be made of one or more cells.

Back to you, which statements do you think are right and which are wrong?

So we've got the statements here.

A, animals are made up of cells.

B, all living organisms are made up of cells.

C, cells are usually big enough for us to see without magnifying them.

Or D cells are like Lego bricks.

They're building blocks that aren't alive.

You can pause the video here and click Play when you've completed this check for understanding.

So what did you get?

Well, A, animals are made up of cells.

I'm sure this is right.

I think this is right.

All living organisms are made up of cells.

You should have ticked the first box or the second box.

Cells are usually big enough for us to see without magnifying them.

Well, this is wrong.

Cells are like Lego bricks, but they are alive.

They're living tissue.

They work together to form living tissue.

Well done if you got that correct.

Let's move on.

Task game.

Some pupils were asked to draw animal cells in a tissue.

Here we've got Aisha's drawing, Jacob's drawing, Laura's and Alex's.

Have a look at all four of them, which is the best drawing of animal cells in a tissue and why?

You can pause the video Here and click Play when you've completed this task.

So how did that go?

Well, let's have a look at all four.

So Jacob's drawing, Aisha's drawing, Alex's and Laura's.

Which is the best drawing of animal cells in a tissue and why?

Jacob's drawing is the best.

The cell.

And this is because the cells are grouped together like building blocks to make a tissue.

Each cell is itself a complete structure or unit.

Aisha's cells are incomplete structures.

So when we look at Aisha's drawing, we can see that the cells are incomplete structures.

Alex's cells are spread apart and grouped together like building blocks.

Laura's cells are too big and would be large enough for us to see without magnifying them.

Well done for completing that task.

Let's move on.

Microscopes are used to view cells.

As you know, most cells are too small to see with our unaided eyes.

Cells can be magnified using a lens.

So here we have one example of a lens.

A magnifying glass has a lens, but even this doesn't make cells appear big enough for us to see them.

And that's where a light microscope comes in.

So a light microscope has two magnifying lenses to make cells large enough to see with our own eyes.

There we've got the eyepiece lens, and this part here is called the objective lens.

A sample of tissue can be magnified, so the individual cells can be seen.

With a light microscope we can see some of the cell structures, but we cannot magnify enough to see atoms and molecules.

Animal cells seen through a light microscope.

This is one example.

Here's a diagram of a cell, including its internal structures.

And this is an example of a molecule.

So these images are not to scale.

Over to you, which of these could you only see by using a light microscope?

Is it A, a cell, B, molecule, C, tissue, or D, water?

What do you think?

You can pause the video here and click Play when you've got the answer.

So what did you get?

Well, if you got A, cell, you are correct.

Let's move on.

Task B.

Andeep and Jun are discussing their aims for using a light microscope.

Andeep says, "I'm going to use a light microscope to look for a water molecule inside a cell.

" Jun says, "I'm going to use a light microscope to look at a single cell.

" I'd like you to explain to Andeep and Jun whether they will be able to achieve their aims using a light microscope any why.

You pause the video here and click Play when you've completed this task.

So how did that go?

Well, you may have got something like this: Andeep would not be able to see any water molecules.

The molecules are too small.

The microscope's lenses cannot magnify molecules enough to see them will.

Jun will be able to see the structure of a cell.

The microscope lenses can magnify cells enough to be able to see them.

He will not be able to see all of the structures inside a cell.

Well done if you've got those key points.

Let's move on.

Lesson cycle three, using a microscope.

So this is a labeled diagram of a light microscope.

We've got the eyepiece lens here, the objective lens there, the stage, the light source, coarse focus wheel, fine focus wheel.

Over to you, I'd like you to add the missing labels to the parts of the microscope.

You can pause the video here And click Play when you've done that.

So what did you get?

Well, we've got the course focus wheel just there.

And this part is known as the light source.

And here we've got the objective lens.

I'd like you to watch the video clip to see how to use the microscope to observe the cells in a specimen.

You can click the Watch button on the slide deck to watch this video.

The method for using a microscope is, one, turn the objective to the lowest magnification.

Two, place the slide on the stage under the clips.

Three, turn on the light source.

Four, looking from the side, turn the coarse focus wheel to move the stage up, so it's close to the objective lens.

Five, looking into the eye piece, turn the coarse focus wheel to bring your specimen into focus.

Six, turn the fine focus wheel to make the image clearer.

Seven the magnification can be increased by changing to a higher power objective lens.

Over to you, put these statements in the correct order for using a microscope to view a slide.

A, use the fine focus wheel to make the image clearer.

B, place the slide on the stage.

C, turn to the lowest power objective lens.

And D, use the coarse focus wheel to focus on the specimen.

You can pause the video here and click Play, once you've competed this check for understanding.

So what did you get?

Well, the first step is to turn to the lowest power objective lens.

Step two, place the slide on the stage.

Step three, use the coarse focus wheel to focus on the specimen.

And the last step, use the fine focus wheel to make the image clearer.

Well done if you ordered those statements correctly.

Let's move on.

Task C, follow the method of using a light microscope to magnify and focus on cells in a tissue specimen from a plant or animal.

I'd like you to also identify a single cell.

You can pause the video here and click Play once you've completed this task.

So how did that go?

So here is an example of an image that may be similar to what you saw through a light microscope.

This is an example of muscle tissue.

You can clearly see each cell.

We've now reached the end of this lesson.

Let's summarize our learning.

So this lesson was to do with observing cells with a light microscope.

You now understand that living organisms are made up of living building blocks called cells.

A sample of cells can be magnified using a light microscope, so the individual cells appear big enough to be seen.

Cells make up tissues and a specimen of tissue can be prepared to be viewed using a microscope.

To use a microscope, the specimen on a slide is placed on this stage.

The microscope is turned to the lowest power objective lens.

The lens will magnify the image.

This makes the cells and some structures inside them large enough to see.

Looking through the eye piece lens, the coarse and fine focus wheels are used to focus the image, so cell structures become clear.

Thank you so much for joining me in this lesson.

Bye!