Hello, my name is Mrs. Mecrin and I'm so excited to be learning all about the human digestive system with you.

Welcome to today's lesson from the unit Introduction to the Human Digestive System.

Your lesson outcome today is I can describe the first part of the journey of food through the human digestive system.

Now this topic might be new to you and you may find it a little bit tricky.

As with all learning, sometimes we can find it a little bit challenging.

However, we are just going to work really hard together and we're going to learn lots of brilliant new things.

Let's begin.

So in bold are all of your keywords for today and along with the keywords you have the definitions for those words as well.

Now I am going to be referring to these throughout today's video, so you don't need to jot them down.

However, if you find that it does help you to have them written down, you can pause the video here and have a go at doing that.

Fantastic, well done.

So our lesson today is split into two sections.

Let's begin with the first section, where the digestive system begins.

Now these children are wondering where the food they eat goes.

And Izzy says, "I think food just stays in our body to give us energy." Jacob says, "I think food just disappears when we've chewed it." And Sam says, "I think the bits of food we don't need come out when we go to the toilet." What do you think happens? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So all of these children have some misconceptions in their understanding of what happens to food once we've eaten it.

So wait, we are going to be going into detail in today's lesson to find out exactly what happens.

Now, humans need food and water to survive and stay healthy.

And the food we eat gets broken down by our body as it goes on a journey through our digestive system.

And our digestive system uses nutrients from food to make our body work and give us energy.

The waste food our body doesn't use is passed out of our body into the toilet.

Now, which of these things do humans need to survive? Is it A, a mobile phone, B, food, C, television, or D, water? So think about those things that we need to survive.

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

Fantastic, well done.

The answers are food and water.

Now, digestion is when food is broken down so that nutrients can be absorbed by the body.

Izzy says, "I think digestion starts in my stomach." Jacob says, "I think digestion starts in my mouth." And Sam says, "I think digestion starts in my throat." Where do you think digestion starts? I'll give you five seconds to think about your answer.

Fabulous, well done.

So food passes through many different organs in our body and this is called the digestive system.

And digestion begins in the mouth, so Jacob was correct.

Now, which part of the mouth do you think is involved or which parts of the mouth are involved with digesting food? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So when food enters the mouth, it begins to be broken down by different teeth, biting, chewing, and grinding, and the mouth produces saliva, which is a watery liquid.

Now, saliva wets the food and helps to prepare it for digestion and the tongue moves the food around the mouth, helping to mix smaller bits of food with saliva to make them easier to swallow.

Which is really interesting because the tongue, as we know, has taste buds on it, which helps us to taste the food, but it also helps us to move the food around our mouth.

Now once all of this has happened, what do you think happens to the food next? Where do you think it goes? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So I'm going to go into a little bit more detail with that in a moment, but let's do a quick, true or false.

Digestion starts when food enters our stomach.

Is that true or false? I'll give you five seconds to think about your answer.

Off you go.

Fabulous, well done, the answer is false.

Now let's see if you can justify your answer.

Is that because digestion starts when our food is being cooked or digestion starts when the food enters our mouth? Again, I'll give you five seconds to think about your answer, off you go.

Fantastic, well done, the answer is B.

Digestion starts when the food enters our mouth.

Now what happens at the start of the digestive system? Is it A, food is put on a plate, and our knife and the fork break down the food, is it B, saliva is produced which starts to break down the food, C, teeth bite, chew and grind the food into smaller pieces, or D, the tongue moves the food around the mouth.

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

Fantastic, well done.

The answers are B, C, and D.

So remember, digestion does not happen until that food enters our mouth.

It's got nothing to do with our knives and forks breaking it down.

Now, Jacob says, "We all have different ideas about where our food goes when we eat.

Now we could draw the journey of food through the human digestive system to present and compare what we think happens." What do you think you would include in your drawing? I'll give you five seconds to think about your answer, off you go.

Fabulous, well done.

Now I'm not going to share it with you just yet because we are going to learn about it in a moment.

So your first task, I want you to draw an outline of a human body and draw what you think happens to the food as it travels through the digestive system.

And I want you to label any parts of the human digestive system that you already know about.

Don't worry if you don't know too many, that's okay because we're going to learn about it together.

Just have a go and see what you can remember or what you already know.

So I want you to pause the video here and have a go at doing that activity.

Off you go.

So, your diagram may have looked a little bit like this, so there may be some incorrect ideas at this stage, that's okay.

So you might have drawn the mouth, the stomach, and the throat.

Don't worry if you've not got them exactly in the right place yet or you didn't think about those parts because we're going to learn a little bit more about it now.

So what I want you to do for your second part of today's activity is to explain to a partner the functions of the teeth, the tongue, and the saliva in the human digestive system.

So what do you use your teeth for? What does the tongue do and how does the saliva help in the human digestive system? So I want you to pause the video now and have a go at explaining that to a partner.

Off you go.

Fantastic, well done.

So you might have said things like the teeth bite, chew and grind the food into smaller pieces.

You've got the tongue which moves food around the mouth and the saliva is produced in the mouth, which makes food easier to swallow.

So were your answers similar or different to that? So now we are on to the second part of our learning today, which is from mouth to stomach.

So we're going to learn a little bit more about the human digestive system now.

So the children are discussing their ideas about the next stage of digestion and Izzy says, "I think the food falls down from your mouth, passes through your chest and lands in your tummy." Sam says, "I think you swallow the smaller bits of food and they are pushed down through a tube which is joint to your stomach." What do you think? I'll give you five seconds to think about your answer, off you go.

Fantastic, well done.

So when you swallow, bits of moist food travel through a tube just for food and drink, which is called the oesophagus.

And food is pushed down your oesophagus by muscles that squeeze and relax.

And this pushes the food through the tube.

Now I want you to gently put your hand on your throat and swallow a few times to feel the top of your oesophagus moving.

So I'll give you five seconds to do that, but if you want to spend a little bit more time, you can pause the video and have a go at that activity.

Fabulous, well done.

So at the back of your throat there's a small flap of muscle which closes to prevent food and liquid from going down a different tube that you use for breathing.

Now how long do you think the oesophagus is? I'll give you five seconds to think about your answer.

Fantastic, well done.

So your oesophagus is only about 15 centimetres long.

So if you think about one of those long rulers that you might use at school, so only half the length of that and it starts at your mouth and it ends at your stomach.

Now let's do a quick checking of your learning.

Where does food go when it leaves your mouth? Is it A, into your chest, B, into your stomach, C into your oesophagus, or D, into your legs.

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

Off you go.

Fabulous, well done.

And the answer is into your oesophagus.

Now true or false, food travels down the oesophagus into the stomach.

Is that true or false? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

And the answer is true.

Now let's see if you can justify your answer.

Is that because A, food falls through your oesophagus into your stomach when you stand up, or B, food is pushed by muscles in the oesophagus and then into your stomach? Again, I'll give you five seconds to think about your answer, off you go.

Fantastic, well done.

The answer is B.

Now your stomach is like a stretchy bag that stores food and helps to break it down.

Now do you think your stomach stays the same size when you eat? Again, I'll give you five seconds to think about your answer, off you go.

Fabulous, well done.

So when your stomach's empty, it's about the size of a tennis ball or your fist, and when you eat a meal your stomach stretches.

Now an adult stomach can stretch to the size of a football to hold as much as four litres of food.

Now let's see what Izzy, Sam, Jacob and Alex have to say about what happens when food reaches your stomach.

Izzy says, "I think the food gets squashed up in my stomach when I walk and move around." Jacob says, "I can hear my stomach rumbling sometimes, so that means it's digesting my food." Sam says, "I think it gets mixed up with water in my stomach and then disappears." And Alex says, "I think food gets broken down further by liquid in my stomach called stomach acid." Now who do you think is right? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So the stomach is like a mixer, churning together all the small pieces of food that come down the oesophagus into smaller and smaller pieces.

Now in the stomach, food is mixed with stomach acids.

So this is where Alex was correct, and this helps to digest food further into a sloppy liquid like a thick soup.

And stomach acid also helps to kill any germs in the food.

Now let's do a quick checking of your learning.

It says which of these things happen during digestion in your stomach? Is it A, food disappears into the stomach walls, B, food is made into bigger pieces again so it can be digested, or C, food is broken down further by stomach acid.

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

Off you go.

Fantastic, well done, the answer is C.

Now Laura says, "I think the human digestive system is tricky to understand because we can't see what's happening to our food once we've swallowed it." Now what could Laura do to help her understand the human digestive system? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So Jun says you could make a model to show what you've learned about digestion so far.

Some models can be used to demonstrate and explain things that we are not able to see or experience for ourselves.

And Laura says, "I need to think about what I could use to represent my mouth, teeth, tongue, saliva, oesophagus, stomach and stomach acid." Do you have any ideas? I'll give you five seconds to think about your answer.

Off you go.

Fantastic, well done.

So you can make a model.

So Laura makes a model to demonstrate how food is digested and she uses everyday objects to represent different parts of the human digestive system.

So can you guess what each object represents in Laura's model? So you've got vinegar, you've got a bowl, got some water there, a banana, you've got what looks like an old pair of tights there, you've got a butter knife, you've got a potato masher.

So what could each of the objects represent in Laura's model? I'll give you five seconds to think about your answer.

Fantastic, well done.

So first, Laura chops a banana, which is the food into a bowl, which is the mouth with a knife and a masher, which are your incisors and your molars.

Next she adds water, which is the saliva, and this moistens the food and prepares it for digestion and the banana breaks down into smaller pieces and mixes with the saliva ready to be swallowed.

Now Laura pours the food into a stocking with the toe removed and this represents the oesophagus and she squeezes the food down the stocking into a clear bag, which is the stomach.

And finally she vinegar to the bag, which represents the stomach acid and squashes the bag to represent the stomach mixing and digesting the food into a thick, sloppy liquid.

Now, true or false.

Models can be helpful in understanding science.

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

Off you go.

Fantastic, well done.

The answer is true.

Now let's see if you can justify your answer.

Is that because models can be used to demonstrate and explain things that we are not able to see or experience for ourselves, or B, models are used instead of having to write things.

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

Fabulous, well done.

The answer is A.

Now it says to create a model or use Laura's ideas to show what happens in the human digestive system from mouth to stomach.

So you will need to include the mouth, the teeth, the tongue, the saliva, the oesophagus, the stomach and the stomach acid.

And I want you to demonstrate your model in action and explain what is happening at each stage from mouth to stomach.

So you are going to need to pause the video here, have a go at this activity, and then come back once you are ready, off you go.

Fabulous, well done.

So you may have got something similar to this, which was the banana being the food, the bowl being the mouth, the knife being the incisors, the mashers were the molars, water was the saliva, stocking was the oesophagus, the sandwich bag was the stomach and the vinegar was the stomach acid.

And it says this is how I use the equipment to model digestion.

I used a plastic knife for incisors and a food masher for the molars to break up the banana in a bowl for my stomach.

I added water to the bowl and mixed it with a spoon to represent my tongue.

I poured the smaller pieces of moist banana into a stocking with the toe removed for my oesophagus and squeezed it to push the food down.

I squeezed the food into a clear sandwich bag for my stomach.

I added a splash of vinegar for stomach acid to the bag and squash the bag to show the stomach digesting the food and stomach acid, breaking the food into smaller pieces.

Now here's the second part of task B.

It says to return to the diagram that you drew in task A, I want you to make any changes or add any new information that you have learned about the human digestive system.

So I want you to pause the video here and have a go at doing that, off you go.

Fabulous, well done.

So now you may have drawn in the mouth with the teeth, the tongue, and the saliva, the stomach containing the stomach acid, the oesophagus, the muscles at the back of the throat.

So now we are on to the summary of our learning today.

Humans need food and water to survive and be healthy.

In the mouth at the start of the digestive system, the tongue moves food around, teeth chop it up and saliva makes it easier to swallow.

Food is pushed down the oesophagus into the stomach where it's broken down further by stomach acid.

Models can be used to demonstrate and explain things that we are not able to see or experience for ourselves.

Now you have worked so hard on your models to represent the human digestive system and you have done lots of fabulous learning.

So well done, I'm so proud of you.