Lesson video

Hello, my name is Mrs. Mehrin and I'm really excited to be learning all about seed formation and seed dispersal with you.

Welcome to today's lesson from the unit, "What plants do and what they need.

" Your lesson outcome is, "I can explain how seeds are formed and dispersed.

" I know that learning can sometimes be a little bit challenging, but that's okay because it just means that we are going to work really hard together and we're going to learn lots of fabulous new things.

Let's begin.

Here are your keywords for today, along with the definition.

Now, I am going to be referring to these keywords and definitions throughout today's lesson.

However, if you find it helpful, you can pause the video here and you can jot them down.

Fantastic, well done.

So, our lesson today is split into the three parts.

And let's begin with the first part, "Fertilization and Seed Formation.

" So, all parts of a plant have a function.

A function of flowers is to reproduce, and this means to make more plants.

So, for reproduction to happen, first the flower must be pollinated.

Pollination happens when pollen from a male anther lands on the female stigma of a flower.

Now here, we have a diagram of that.

So, we've got the pollen from one flower and it needs to land on another flower, in the female stigma.

So, after pollen has landed on the stigma, it moves down to the flower's ovary, and this is called fertilization.

So, what happens when pollen reaches a flower's ovary?

Is it A, pollination, B, fertilization or C, germination?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

The answer is B, fertilization.

So, when the plant has been fertilized, seeds grow inside the ovary just like this.

And here we have lotus seeds forming in the ovary.

And this is called seed formation.

Sometimes the ovaries develop into fruits that we can eat as the seeds are forming.

So, what is seed formation?

Is it A, when seeds develop inside an ovary?

B, when seeds are planted in soil?

Or C, when flowers die and the seeds drop off the plant.

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

The answer is A, when seeds develop inside an ovary.

Now, Aisha has been learning about pollination and seed formation, and she says.

"Pollen has to move from one place to another for plants to reproduce.

I think pollen is just very tiny seeds.

" Do you agree with Aisha?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, pollen grains cannot grow into a new plant because they are not seeds.

Flowers need pollen to land on their stigma and move to the ovary for fertilization to happen.

Then they can form seeds.

So, pollen can't make or turn into seeds without the help of fertilization.

Now, let's do a quick check-in of your learning so far.

True or false?

Pollen grains are very small seeds.

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done, the answer is false.

So, why do you think that is?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, pollen can't grow into a new plant like seeds can.

Pollen must land on the stigma to fertilizer the flower, then the flower can form seeds.

So, here is your first task for today.

It says, add the missing words to explain how flowering plants reproduce.

You may not need to use all of the words here on the right hand side.

So, something happens when pollen from a male something lands on a female something.

The pollen moves into the something of a flower.

This is called something.

Seed something happens inside the ovaries.

So, you're going to fill in those blanks using some of the words from the right hand side here.

So, I'd like you to pause the video now and have a go at doing this.

Off you go.

Fantastic, well done.

So, pollination happens when pollen from a male anther lands on a female stigma.

The pollen moves into the ovary of the flower.

This is called fertilization.

Seed formation happens inside the ovary.

Now, we are onto the second part of our learning, which is called, "Seed dispersal.

" So, after the seeds have formed, many plants spread their seeds over a wider area, and this is called seed dispersal.

Why do you think plants need to do this?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, if there are lots plants all growing in the same small place, it might not survive.

So, to survive, all plants need nutrients, water, light, and they need space to grow as well.

And there may not be enough of all of these things for all of the plants if they all grow too close together.

So, each new plant will be more likely to get everything it needs to survive and grow if the seed is dispersed away from the other seeds and its parent plant.

So for example, look at the ground beneath this large oak tree.

What do you notice about it?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So Sofia says, "I can't see any other plants growing underneath the oak tree.

" That's because sunlight is blocked by the oak's tree branches, so there may not be enough for other plants to grow underneath it.

Now, the roots of the oak tree will also be absorbing a lot of water and nutrients in the soil, so there may not be enough for other plants to grow.

Now, if the oak tree's seeds are dispersed, they will not need to compete with the parent plant or other new plants for light, water or nutrients and will be more likely to survive.

So, what is seed dispersal?

Is it A, when seeds are spread far away from their parent plant?

B, when seeds are formed inside the ovary?

Or C, when seeds are transferred from one flower to another by insects?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So it's A, when seeds are spread far away from their parent plant.

Now, plants disperse their seeds so it's less likely the new plants will A, be pollinated again and make more seeds.

B, survive and grow into large plants, or C, have to compete with others for water, light, and nutrients.

Again, I'll give you five seconds to think about your answer.

Off you go.

Fabulous, the answer is C, plants disperse their seeds so it's less likely the new plants will have to compete with others for water, light, and nutrients.

Now, here is your second task for today.

It says, carry out the modeling activity to explore how plants may or may not survive when they are in competition with other plants.

Follow the instructions provided by an adult, then use what you notice to answer the question, why are new plants more likely to survive and grow if the parent plant disperses its seeds?

So, I'd like you to pause the video here and have a go at doing this activity.

Off you go.

Fabulous, well done.

So, Izzy says, "I pretended to be a plant and tried to gather the things I needed to survive.

It was not easy to get everything I needed when there were lots of other plants all trying to get them too, and my plant died.

It was much easier to get everything I needed when the other plants were far away from me.

More of the plants were able to survive when we were spread further out.

" Did you notice the same thing as Izzy?

I know I did.

So, now we are onto the final part of our learning today, "How seeds are dispersed.

" So, Andeep has been learning about seed dispersal and he says, "Plants can't move from place to place in the same way that animals can, so how do they spread their seeds around?

" What do you think?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, different types of plants disperse their seeds in different ways.

Some plants that grow near water have seeds that can float, so they can be carried away to other places by the flow of the water.

So, for example, once the seed drops from the parent plant, it might fall into a nearby river or the sea, and then they can be carried away to other places by the flow of that water.

So, seeds that are dispersed by water are able to A, fly, B, float or C, sink.

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

The answer is B, float.

Now, some plants have seeds that are dispersed by the wind.

These seeds can be very lightweight or they can have a shape that helps them to travel in the wind.

Now, which of these seeds is not likely to be dispersed by the wind.

Is it A, milkweed, B, horse chestnut or C, maple.

So, think about what the wind would do to the seed.

Which of these is not likely to be dispersed by the wind?

I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

The answer is B, the horse chestnut because it's not lightweight.

Now, seeds can also be dispersed by animals, and some seeds grow inside fruits which the animals eat.

And here we have a squirrel eating fruits that contain seeds, and we've also got a bird there as well.

Now later on, the seeds leave the animal when it passes waste.

Some plants disperse their seeds by explosion.

So, these plants have seed pods that pop open and scatter their seeds around them.

Now, which of these seeds are likely to be dispersed by animals and which by explosion?

So, you've got the Himalayan balsam, the burdock, and the strawberry.

So, I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So, the Himalayan balsam by explosion and the burdock and the strawberry by animal.

So, with the burdock, it would probably stick to the animal's fur and then fall off later.

And with a strawberry, an animal would eat it and then it would leave the animal through its waste.

Now, here is your final task for today, and it says, carefully observe each seed and decide how you think it's dispersed.

Is it A, by water, B, by wind, C, eaten by animals, D, caught on animal fur, or E, explosion?

So again, I'd like you to pause the video here and have a go at doing this activity.

Off you go.

Fantastic, well done.

So, water would be the coconut, wind, the dandelion, and you will have often seen dandelion seeds flying about, especially in spring.

C, eaten by animals would be the holly.

The galium would be caught on animal fur and the explosion would be the okra.

And you can see all the lovely seeds in there.

Now, with the okra, that could also be through being eaten by animals and then coming out through the waste as well.

Now, explain how each seed is suited to its method of dispersal.

So, I'll give you some time now to do this.

I'd like you to pause the video and have a go.

Off you go.

Fantastic, well done.

So, coconut seed can float so it can be dispersed by water.

The dandelion seeds are lightweight so they can blow away in the wind.

The holly has berries that birds like to eat, so, these will be dispersed by animals.

The galium seeds are covered in tiny hooks that can stick to animal fur and get carried away, and the okra seeds grow in seed pods that can explode.

Now, we are onto the summary of our learning today.

So, plant reproduction starts with pollination when pollen from a male anther lands on a female stigma.

Fertilization happens when this pollen moves down to the flower's ovary.

Seeds are then formed and can be dispersed by wind, water, explosion or animals.

Seeds are dispersed so they won't have time to compete with other seeds from the same parent plant for the things they need to survive.

Well done for today.

You've done some fantastic critical thinking and thought really carefully about seed formation and seed dispersal, so well done.