Investigating String Telephones

This week I asked the senior classes whether they thought sound could travel through things apart from air.

They thought sound could travel through water and solid things.
This is correct.

The next challenge was to test how well sound travels through a string telephone. String telephones work because when a person talks into the cup the sound waves travel along the string to the person at the other end.
There were 12 different types of string telephones to test. The aim was to find out which type of cup and which type of string allowed the sound waves to travel the best.

4 types of cups - plastic, paper, polystyrene, tin can
3 types of string - wool, cotton, plastic

Before students began they had to predict which combination would work the best. Most people thought the tin can and plastic string telephone would work the best.

However, after testing the different types of string telephones they found out that the plastic cup with the cotton string worked the best because you could easily hear the words.
Students then had to come up with a theory as to why this combination of string and cup allowed the sound vibrations to travel the best.

Energy From The Wind

This week at Science Club we were learning about wind. We found out that wind is caused when hot air rises and cooler air moves in to take its place.

We made whirling snakes.
When you hold them over heat they spin clockwise.
When you hold them over cold they spin anti-clockwise.
The hotter or colder it is below them the more they spin.

We also had a go at making windmills. This was quite tricky but Bradley managed to make his work well. When the windmill turned it pulled up the load (blutac) at the back.


Windmills can be used to generate electricity. These types of windmills are called wind turbines. This way of generating electricity is a good one because wind energy is renewable and wont run out.

Check out these websites for more information:

• NZ wind energy association
• Interactive wind energy activities
  

Myth Busters

Have you noticed that whenever you drop a piece of toast off your plate it always seems to land buttered side down. Toast is not so yummy with furry bits on your peanut butter.

The Year 5 and 6 students investigated this to find out if it is a myth or an actual fact.



This is what they found out....

Alana and Alice
The toast doesn't always land butter side down. We got 15 for up and 13 for down. It's a 50/50 chance. We think we got that result because of the way we dropped it and the height and size of the toast.

Billy and Harrison
The toast fell on the buttered side more often than the non-buttered side. I think it was because of the weight of the buttered side.

Shikhar and Jack
Whichever side was facing down when you dropped the toast - the opposite side would land on the newspaper. For example - if you start with the non-buttered side facing down after the drop the buttered side is facing the ground.
When me and Jack tested toast cut into quarters, every time it landed on the buttered side down. It is because the toast was small and had time to turn and flip.

Cameron and Max
We think that the buttered side landed face down the most because it had more weight on it.

Bradley and Russell
We don't know why it ended up like this but it might be possible it was the way we tested it. The buttered side faced up most often. Our final results were:

• Buttered side down 15/40
• Buttered side up 25/40

Ella and Louise
We found out that butter side mostly landed up with 19/28. We dropped the toast from waist height so it mostly flipped once.

So the overall results were:

• 3 groups found buttered side up happened most often.
• 3 groups found buttered side down happened most often.

There is a 50% chance of the toast landing buttered side down and we think it depends on:

• The height of the drop.
• The angle of the drop.
• The size of the toast.
• Which side of the toast is up on the plate.

So we think this myth has been busted!

Toast does not always land buttered side down.

Was that sound high or low?

When you listen to sounds sometimes they are high and sometimes they are low. This is called their PITCH. This week the Year 5 and 6 classes investigated pitch to find out why some sounds are high and some are low. This is what they found out.

These are Boomwhacker tubes. When you hit them on the ground they make a sound. Each tube makes a different sound because they are different lengths. The air inside the tube vibrates.

Blowing into the bottles makes the air vibrate which produces a sound. Each bottle has a different amount of water in it. The bottle with lots of water and a little bit of air made a high sound. The bottle with a little bit of water and lots of air made a low sound.

The opposite happened when we tapped the bottles with a pencil. This is because when you tap the bottles it is the water that vibrates to make the sound and not the air.

Each test tube has a different amount of water in them so when you blow across the test tubes they make different sounds. When there is lots of air the sound is low pitched. When there is not much air the sound is high pitched.

These chime bars are different lengths so when you hit them they play notes of different pitch. When you hit the bars they vibrate to make the sound. The long bars play a low note and the short bars play a high note.

From doing these investigations we discovered that...

When the part that is vibrating is small the vibrations are closer together (high frequency waves) so the sound is high pitched. When the part that is vibrating is bigger the vibrations are further apart (low frequency waves) so the sound is low pitched.

Water Surface Tension

All things (including water) is made up of tiny things called molecules. Water molecules like each other and stick together. That is why when a bit of water falls on a table or window it blobs together in a little droplet.

The surface of the water has a layer of clingy molecules on it. This layer is called the water's surface tension.

The students in the Year 5/6 science club did some investigations to demonstrate surface tension.

In the first investigation we dropped drops of water onto a coin and counted how many it could hold before it overflowed.


We tested clean water and soapy water. We found that clean water was able to hold a lot more drops that soapy water. The average for clean water was 24. The average for soapy water was 14.

We thought this was because the soap took up more space on the coin because of the bubbles. But Miss Harrison explained to us that the soap breaks the surface tension of the water so the bubble is not as strong.

This investigation showed what happens when the surface tension on the water was broken. First we sprinkled pepper on top of the water. Then we dipped our finger in soap and then dipped it into the middle of the bowl. The pepper suddenly spread away from our finger.


This video showed what we did for our last investigation. (Sorry about the sideways shots - Miss Harrison had her camera turned around the wrong way!)


This is what we learned during the lesson.

Jack
Water likes to stick together but the soap separates it when it breaks the surface tension.

Shikhar
The dishwashing liquid molecules breaks the surface tension of the water so the toothpicks separate from each other as the water moves.

Russell
The soap breaks up the surface tension. This works because water molecules like to stick together. But since soap likes to break things up it moves the water away to the sides.

Some things are magnetic

This term the junior classes are learning about magnets.

Today they found out that magnets stick to some things but not others.

The things that magnets stick to are called magnetic.

In groups students looked at a collection of objects and guessed whether they thought they would be magnetic or not. These charts show their predictions.



Next the students used a magnet to test each object. These charts show which objects were magnetic and could be picked up by the magnet and which were not magnetic.

We found out that....

• Magnets stick to some metals but not others.
• Magnets do not stick to plastic, wood, stone, glass or fabric.
  

Sound is all about vibrations

This term it is the senior classes turn to investigate sound.

In our first lesson we found out that sound is a form of energy that travels as a sound wave which makes a vibration.

We hear the sound when the sound wave reaches our ears.

Diagram from Kids' Health

The sound wave enters the ear and causes the ear drum to vibrate. The sound vibration is passed onto 3 tiny bones called the hammer, anvil and stirrup which pass the sound into the cochlea where the vibrations are turned into a signal that goes to the brain. The brain then works out what the sounds are and where they are coming from.

The investigations we did helped us to see and feel vibrations made by sound waves.

In this investigation we had to talk through the cardboard megaphone at the salt on top of a gladwrapped bowl. We observed that the salt moved around and sometimes jumped. The explanation for this is that the sound waves coming through the megaphone make a vibration that is passed onto the gladwrap. As the gladwrap vibrates the salt moves. When we talked quietly the salt hardly moved but when we talked loudly the salt jumped a lot. This is because loud noises create strong vibrations and quiet noises create weak vibrations.

During this investigation we used a tuning fork. When a tuning fork is hit it starts to vibrate and makes a ringing sound. We were able to see the vibrations by gently touching the tuning for on the water. When we did this the vibrations made ripples in the water and sometimes the water splashed out too.

When you talk at a balloon you can feel the vibrations made by the sound wave. Your fingers that hold the balloon start to vibrate and tickle a bit.

We could also feel the vibrations from the sound wave when we hummed against a piece of paper on a comb. Our lips went all tingly and it felt strange. We also discovered that we could make some pretty cool sounds (especially Mr Mills).