0:00:05 > 0:00:08# If you've got a question and you don't know where to go
0:00:08 > 0:00:11# Ask Nina for some help Cos she's got a science show
0:00:11 > 0:00:15# She makes sense of her senses While helping all her fans
0:00:15 > 0:00:17# By doing her experiments with potions and with bangs
0:00:17 > 0:00:19- # Touch your tongue - Tongue
0:00:19 > 0:00:20- # Fingers - Fingers
0:00:20 > 0:00:22- # Eyes- Eyes - Ears- Ears
0:00:22 > 0:00:23- # Nose- Nose
0:00:23 > 0:00:26# Nina and the Neurons find out what you need to know
0:00:26 > 0:00:29# Nina and the Neurons find out what you need to know
0:00:29 > 0:00:32# Luke, he helps us with our eyes, and Felix with our touch
0:00:32 > 0:00:36# Ollie sniffs out smells and scents, and Belle, she hears so much
0:00:36 > 0:00:38# Bud is Ollie's brother he helps us with our taste
0:00:38 > 0:00:41# They're Nina's little Neurons and they're coming to your place
0:00:41 > 0:00:43- # Touch your tongue - Tongue
0:00:43 > 0:00:44- # Fingers- Fingers
0:00:44 > 0:00:46- # Eyes- Eyes - Ears- Ears
0:00:46 > 0:00:47- # Nose- Nose
0:00:47 > 0:00:50# Nina and the Neurons find out what you need to know
0:00:50 > 0:00:53- # Yeah!- Nina and the Neurons find out what you need to know
0:00:53 > 0:00:54# Oh, yeah! #
0:00:57 > 0:00:58NINA HUMS TUNE
0:01:00 > 0:01:02Oh, hello there.
0:01:02 > 0:01:06How odd - I've turned the tap off but I can still hear running water.
0:01:06 > 0:01:09Oh, no, my bucket's got a leak in it.
0:01:09 > 0:01:11I'll need to find something to block the hole.
0:01:11 > 0:01:13- Hmm. - BEEPING
0:01:13 > 0:01:17Oh. I hear a beep, I see a flash, I wonder what they're going to ask.
0:01:19 > 0:01:21BEEPING STOPS
0:01:21 > 0:01:24ALL: Hi, Nina!
0:01:24 > 0:01:30- Hi.- We've got a question for you. - Why do beavers build dams?
0:01:30 > 0:01:34Oh, that's a great question. Why do beavers build dams?
0:01:34 > 0:01:38Now, a dam is something that stops the water in a stream.
0:01:38 > 0:01:40But why do beavers build them?
0:01:40 > 0:01:43Why don't you come down to my workshop and we'll investigate?
0:01:43 > 0:01:47- ALL: See you soon, Nina, bye!- Bye.
0:01:47 > 0:01:50Well, I'm going to need some help to answer this one,
0:01:50 > 0:01:52and I know just who to ask.
0:01:52 > 0:01:54OK, Neurons, time to get to work!
0:02:11 > 0:02:13ALL: Neurons at the ready, Nina!
0:02:13 > 0:02:16OK, today's question is why do beavers build dams?
0:02:16 > 0:02:19Which Neuron do you think will be most useful
0:02:19 > 0:02:22in helping us find the answer?
0:02:22 > 0:02:24It's Belle.
0:02:24 > 0:02:26CHEERING
0:02:26 > 0:02:29CHANTING: Go, Belle! Go, Belle! Go, Belle!
0:02:31 > 0:02:34Brilliant! I'm all ears, Nina.
0:02:34 > 0:02:38Today's question is why do beavers build dams?
0:02:38 > 0:02:41Beavers build dams on splashy, noisy streams,
0:02:41 > 0:02:44so Belle will be helping me today, but stand by, Neurons,
0:02:44 > 0:02:47I've a feeling I may need help from all of you.
0:02:47 > 0:02:50Right, I need to get the workshop ready
0:02:50 > 0:02:52before the Experimenters arrive.
0:02:54 > 0:03:00Bethan likes swimming. Rhianna loves drawing. Corey likes playing golf.
0:03:00 > 0:03:04But they all want to know - why do beavers build dams?
0:03:04 > 0:03:08So today, for one day only, Bethan, Rhianna and Corey become...
0:03:08 > 0:03:11the Experimenters!
0:03:15 > 0:03:17- Hi, guys.- ALL: Hi, Nina.
0:03:17 > 0:03:21Welcome to my workshop and thank you for your great question.
0:03:21 > 0:03:23Why do beavers build dams?
0:03:23 > 0:03:26Well, first, let's have a look at some beavers in action.
0:03:26 > 0:03:31LUKE: Wow, would you look at those beavers? They're so busy.
0:03:31 > 0:03:35- BELLE:- And listen to the beautiful sound of the stream.
0:03:35 > 0:03:36BELLE GASPS
0:03:36 > 0:03:39- What are the beavers doing? - Carrying sticks.
0:03:39 > 0:03:42Yeah, and they're carrying them in their mouths.
0:03:42 > 0:03:45- BUD:- Eugh! Twigs wouldn't taste too good!
0:03:45 > 0:03:49- What do you think they're doing with them?- Building a dam?
0:03:49 > 0:03:52Yes, beavers are the only animals to build dams,
0:03:52 > 0:03:55and they build them in streams
0:03:55 > 0:03:59and use lots of materials that they find nearby to make them strong.
0:03:59 > 0:04:03Let's do an experiment to find out what dams do.
0:04:03 > 0:04:07ALL: Whoo-whoo! An experiment! We're ready, Nina.
0:04:07 > 0:04:10So, we are going to make a dam.
0:04:10 > 0:04:14I'm going to make the pretend stream using this watering can,
0:04:14 > 0:04:18and you guys are going to build the dam using those sandbags.
0:04:18 > 0:04:21- Are you ready?- ALL: Yeah!
0:04:21 > 0:04:23Here comes the stream - go, go, go!
0:04:26 > 0:04:28NINA GIGGLES
0:04:29 > 0:04:31That's it.
0:04:33 > 0:04:34That's good.
0:04:36 > 0:04:39Squash them together, squash them right up.
0:04:46 > 0:04:47Excellent.
0:04:49 > 0:04:54Fantastic job. So, what happened to my stream?
0:04:54 > 0:04:59- The sandbags got in the way.- Yes, they slowed the stream right down.
0:04:59 > 0:05:02- And what happened to the water? - It made a puddle.
0:05:02 > 0:05:06Yes, it made a little pool here.
0:05:06 > 0:05:09So dams slow down the flow of water in a stream.
0:05:09 > 0:05:14The water builds up and creates a pool that wasn't there before.
0:05:14 > 0:05:17Of course it's not just beavers that build dams.
0:05:17 > 0:05:22That's right, Felix, people build dams too. Have a look at this.
0:05:22 > 0:05:24This dam is built by people,
0:05:24 > 0:05:29and it's so big that it's created a lake behind it called a reservoir.
0:05:29 > 0:05:33And reservoirs store water for people to drink.
0:05:33 > 0:05:36LUKE: So beavers make dams in streams.
0:05:36 > 0:05:39- BELLE:- The dam slows down the stream and makes a pool.
0:05:39 > 0:05:40BELLE LAUGHS
0:05:40 > 0:05:43Why do beavers make a pool?
0:05:43 > 0:05:44That's a great question.
0:05:44 > 0:05:49I think we need to go somewhere very wet to find out more.
0:05:54 > 0:05:58Oh, goody, I love this bit. I wonder where Nina is taking us.
0:05:58 > 0:06:02Nina said somewhere wet, where could that be?
0:06:02 > 0:06:06- BUD:- Maybe a paddling pool, or the seaside!
0:06:06 > 0:06:10- I can hear water, ha-ha. - And I can see trees.
0:06:10 > 0:06:12Looks like we've arrived!
0:06:13 > 0:06:17So, you asked, "Why do beavers build dams?",
0:06:17 > 0:06:20and so far we've found out that beavers build dams in streams
0:06:20 > 0:06:25and the dam makes a pool, but now we want to know why they make a pool.
0:06:25 > 0:06:28So we've come to this forest where some clever beavers
0:06:28 > 0:06:30live in the wild.
0:06:30 > 0:06:33Wow! Are we going to see a real-life beaver?
0:06:33 > 0:06:37Sorry, Bud, beavers are actually very shy, and they usually
0:06:37 > 0:06:41only come out at night, so we might not see one today.
0:06:41 > 0:06:44But we will see something amazing that they've built.
0:06:44 > 0:06:51- Have a look at these. Do you see these marks?- Yeah.
0:06:51 > 0:06:54Yes, well, these are teeth marks from where
0:06:54 > 0:06:56the beaver's been gnawing at the tree.
0:06:56 > 0:06:58- NINA GIGGLES - Have a look at this.
0:06:58 > 0:07:00Beavers eat bark and leaves,
0:07:00 > 0:07:04and they also use the branches to build with, so they can
0:07:04 > 0:07:07nibble away at a tree with their very strong teeth
0:07:07 > 0:07:09until it falls over.
0:07:11 > 0:07:12NINA LAUGHS
0:07:12 > 0:07:17- Now, what do you think this is?! - Oh, a beaver dam.
0:07:17 > 0:07:20Yes! It's a dam that the beavers built.
0:07:20 > 0:07:23LUKE: Wow, look at the big pool they've made.
0:07:23 > 0:07:27- Do beavers live in the dam? - That's a great question, Rhianna.
0:07:27 > 0:07:31Actually, no, they don't. They build themselves a home called a lodge.
0:07:31 > 0:07:34They build it in the pool so the doorway is under water,
0:07:34 > 0:07:37to keep them safe from predators.
0:07:37 > 0:07:40They must be very strong to carry all those logs and branches!
0:07:40 > 0:07:43Beavers are very strong, Belle,
0:07:43 > 0:07:46and they have a very clever way of moving big branches about.
0:07:46 > 0:07:51So I think we need to do another experiment to find out more.
0:07:52 > 0:07:56Now, beavers collect branches and store them in their lodge.
0:07:56 > 0:07:58And we have two tree branches here
0:07:58 > 0:08:00and we're going to try and move them.
0:08:00 > 0:08:03They're about the same size and weight,
0:08:03 > 0:08:07and Corey and Bethan, you guys are going to go together and try
0:08:07 > 0:08:09and move your piece of wood along the water.
0:08:09 > 0:08:12You and I are going to go together, Rhianna,
0:08:12 > 0:08:15and we're going to move it along the ground.
0:08:15 > 0:08:20- So, everyone, pick up your piece of rope. Are you ready?- ALL: Yeah!- Go!
0:08:22 > 0:08:23NINA GASPS
0:08:23 > 0:08:26Okey doke. Now, what do we think was easier?
0:08:26 > 0:08:30- Moving the branch along the water or the ground?- Water.
0:08:30 > 0:08:33Yes, wood floats, so beavers move branches in the water because
0:08:33 > 0:08:38it's much easier than dragging them along the ground with their mouths.
0:08:38 > 0:08:41OLLIE: So beavers build their dam to make a pool.
0:08:41 > 0:08:44- BELLE:- So it's easier for them to move branches around.
0:08:44 > 0:08:48- Well remembered, Neurons. - How do they build the dam, Nina?
0:08:48 > 0:08:50That's a great question.
0:08:50 > 0:08:54I think we need to do one final experiment to find out.
0:08:55 > 0:08:59Your question was, "Why do beavers build dams?"
0:08:59 > 0:09:03And so far we've found out that beavers build dams to make pools,
0:09:03 > 0:09:05and they float branches on the pools
0:09:05 > 0:09:08because it's the easiest way to move them.
0:09:08 > 0:09:11But now we want to know HOW they build their dams.
0:09:11 > 0:09:15- So, do you think we can build a dam like the beavers?- ALL: Yeah!
0:09:15 > 0:09:16Yes, I think can we too.
0:09:16 > 0:09:20So we're going to build a dam across this stream.
0:09:20 > 0:09:24But remember - you should never play near water without an adult.
0:09:24 > 0:09:27Beavers start by building a strong base,
0:09:27 > 0:09:30and they would use heavy materials like big branches.
0:09:30 > 0:09:33- So, shall we give it a go?- ALL: Yes!
0:09:33 > 0:09:35OK, whoo-hoo!
0:09:35 > 0:09:37Oh, oh...
0:09:39 > 0:09:42NINA SIGHS
0:09:42 > 0:09:46Yeah, let's get them nice and close together, really good.
0:09:46 > 0:09:49OK, so more big branches I think.
0:09:51 > 0:09:53NINA GRUNTS
0:09:54 > 0:09:57Oh, that's lovely. This is great teamwork, guys,
0:09:57 > 0:10:01and do you know, beavers work in teams just like this.
0:10:01 > 0:10:04- Do Neurons work in a team too? - OTHERS: Yes, Bud!
0:10:07 > 0:10:10Now we need some smaller branches.
0:10:17 > 0:10:18Ah, that's good.
0:10:38 > 0:10:41Great dam-building, Experimenters!
0:10:41 > 0:10:44So we put the big pieces of wood down first,
0:10:44 > 0:10:46and then smaller branches next.
0:10:46 > 0:10:50And look, the branches are slowing the stream down.
0:10:50 > 0:10:52It's still letting water through.
0:10:52 > 0:10:56- BELLE:- I can hear water trickling through the gaps, Nina, ha-ha!
0:10:56 > 0:11:00You're right, the dam still has lots of holes in it,
0:11:00 > 0:11:04letting the water through, but that's the same with beaver dams.
0:11:04 > 0:11:07Can you guess what they use to block the holes?
0:11:07 > 0:11:09- Mud.- FELIX: Not mud, Nina,
0:11:09 > 0:11:12it's all cold and squidgy - ugh!
0:11:12 > 0:11:15Yes, the beavers get mud from the banks of the stream
0:11:15 > 0:11:20with their paws, and then they pat it onto the dam to block any holes.
0:11:20 > 0:11:24And they listen to the dam, and if they can hear a trickling sound,
0:11:24 > 0:11:27they know there are still some holes to be blocked.
0:11:27 > 0:11:31- BELLE:- Beavers have very good hearing, listening out for all
0:11:31 > 0:11:34the leaks in the dam and filling them out with mud.
0:11:34 > 0:11:37Beavers' dams usually let a trickle of water through,
0:11:37 > 0:11:40that helps keep the pool nice and fresh.
0:11:40 > 0:11:42Come on, guys, let's take the dam down.
0:11:42 > 0:11:46You should always leave the countryside the way you found it.
0:11:46 > 0:11:48# Nina and the Neurons! #
0:11:51 > 0:11:52So, your question was,
0:11:52 > 0:11:56"Why do beavers build dams?" And I think we've answered it.
0:11:56 > 0:12:00LUKE: We learnt that beavers build dams with wood to make a pool.
0:12:00 > 0:12:03- FELIX:- They build their lodge in the pool to keep them safe.
0:12:03 > 0:12:07- OLLIE:- They use the pool to float and move branches.
0:12:07 > 0:12:10BELLE: Beavers block the holes in the dam with mud,
0:12:10 > 0:12:13then they listen to see if their dam has any leaks.
0:12:13 > 0:12:17- So, I hope that's answered your question.- ALL: Thanks, Nina, bye!
0:12:17 > 0:12:20You're welcome, bye.
0:12:22 > 0:12:26If you want to know more about the science that's all around us,
0:12:26 > 0:12:29go to the Nina section on the CBeebies website.
0:12:29 > 0:12:30Have fun!
0:12:30 > 0:12:32# Super structures
0:12:32 > 0:12:34# Super structures
0:12:34 > 0:12:38# Super structures, super structures, super structures!
0:12:38 > 0:12:41# Some of them are tall, some of them are wide
0:12:41 > 0:12:44# They're bumpy, lumpy, wiggly too
0:12:44 > 0:12:46# Wiggly too!
0:12:46 > 0:12:49# Some of them are strong, some of them are small
0:12:49 > 0:12:50# Like me!
0:12:50 > 0:12:52# They're windy, whirly, wishy too
0:12:52 > 0:12:54# All around... #
0:12:54 > 0:12:56Look over here!
0:12:56 > 0:12:59# Build it, stack it, pile it up
0:12:59 > 0:13:02# Come on, let's get building
0:13:02 > 0:13:04# Building, building
0:13:04 > 0:13:07# Race it, hold it, make it stick
0:13:07 > 0:13:12# Come on, let's get building
0:13:12 > 0:13:14# Come on, let's get building
0:13:17 > 0:13:21# Some of them are cosy-warm, some of them are chilly... #
0:13:21 > 0:13:23Brrr!
0:13:23 > 0:13:24# Keep us safe and hide us too
0:13:24 > 0:13:26# Hide us too!
0:13:26 > 0:13:29# Some of them are just for fun or help us to stay dry
0:13:29 > 0:13:32# They're underground and high up too
0:13:32 > 0:13:36# Look around! Over here!
0:13:36 > 0:13:39# Build it, stack it, pile it up
0:13:39 > 0:13:42# Come on, let's get building
0:13:42 > 0:13:44- # Building!- Building!- Building!
0:13:44 > 0:13:48# Race it, hold it, make it stick
0:13:48 > 0:13:51# Come on, let's get building
0:13:51 > 0:13:56# Come on, let's get building! #
0:13:56 > 0:13:59And remember, there are superstructures everywhere.
0:13:59 > 0:14:04Whether they're big or small, wide or tall, we can all get building.
0:14:04 > 0:14:06See you again soon, bye!
0:14:06 > 0:14:08ALL: Bye!
0:14:08 > 0:14:09Get building!