Science Showcase

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Fun with Rockets

Today was our last Science Club session for 2010 so we ended it with a BANG by making 2 different types of rockets.

One rocket was made out of a plastic bottle and an air pump. The other rocket was made by putting baking soda and vinegar in a film cannister. Both rockets work the same way really. As the rocket container fills up with gas (air or carbon dioxide) the pressure builds up. When there is so much pressure the cork pops out or the lid pops off and the rocket flies into the air.

Pumping air into the rocket. Everyone is getting ready to catch the rocket when it lands.

Shikar
Today I had a go at bottle rockets. I made 4. On my third one I pumped for a long time but as soon as I gave up and sat down, the rocket blasted off about 20-25 metres above the ground. I got to perform 2 of my rockets in from of an audience of junior kids. They liked both of mine. On one of my rockets, when it shot of some water splashed onto my shorts and new jersey. Mum won't be happy!

I learnt a new thing today! When the water was in the bottle the air I was pumping was making pressure. If you have lots of water or not water the bottle will only go about 5-10 metres high above the ground. I wonder what will happen if we put vinegar instead of water?

Alice
When we did the experiment we had an air pump, a bottle and water and a cork. First of all we filled quarter of the bottle with water. We used the air pump to fill up the bottle with air pressure. When the bottle is filled up with air pressure it shoots up into the sky.

This photo shows how to get the rocket ready by jamming the cork into the bottle.

Alana
To launch the big rocket you need to pump the pump to make it fly up. Make sure you stand far away unless you are launching it. You can fill the bottle up with as much water as you want but we found that it works better when the bottle is quarter full. If you're finding your rocket is taking a long time to blast off it means it should go higher. It works because the air getting pumped into it fills up the bottle and when there is not enough room left it pops the cork off the bottom.

Jack
I found out that the best rockets were the big bottles with water up to the first line from the bottom. This is because there was enough water and enough room for the air pressure to help push but not too much water to weigh it down.

Max
The rocket made from a lemonade bottle quarter filled with water worked the best. I think this worked because there was lots of space for air to go so when the bottle was full of air the cork came out really fast, giving it a height boost.

Billy
Today I had a go at making bottle rockets. To make a bottle rocket you have to fill a lemonade bottle quarter full with water. The rocket is powered by the water and the water acts as a jet because it pushes the bottle up. AWESOME.

Harrison
My rocket went wild. It was facing north and it landed west. Totally opposite. All of mine worked except one. The pipe busted but we fixed it. The rocket worked because the water in the bottle was taking up space and there was no more room for the air we pumped in. So there was too much air and the cork flew off and the air pushed it up into the air.

Louise
We used a foot pump and we could see the air bubbling up inside. The rocket worked because it had too much air pressure so it had nowhere to go but up. The worst working bottle was the vinegar bottle and the best bottle was the lemonade bottle.

Cameron
First we got a bit of baking soda and wrapped it in a tissue and put in in the film cannister. Then we got the vinegar and tipped it in and quickly put the lid on. After a while the cannister pushed the lid off and it went really high.

The experiment worked best when there was less baking soda, less vinegar and if you put the lid on quickly.

What effect does friction have on rolling marbles?

WHAT IS FRICTION?
Friction occurs whenever 2 surfaces move against each other. Friction tends to slow movement down.

Sometimes we want lots of friction (eg - so car tyres grip the road, so our shoes don't slip on the floor, so our hands don't slip off the cricket bat).

Sometimes we don't want friction (eg - on a water slide, when we are skiing or ice-skating).

This week the middles have been finding out about which type of surface has the most friction. We tested this by rolled a marble down a ramp then onto different types of surfaces. When the marble stopped rolling we measured the distance it had rolled.

The test surfaces were:

• carpet
• cardboard
• newspaper
• towel

Which surface do you think let the marble roll the furthest?

This is what the marble ramp looked like. In this photo we are testing the cardboard race track.
We let the marble go at the top and watched it zoom down.

Next we had to measure the distance that the marble rolled. We had to use our maths skills to measure accurately and add up the measurements when the marble rolled further than the length of the ruler.The whole team had to work together on this task.

WHAT DID WE FIND OUT?

We found out that the cardboard race track let the marble roll the greatest distance. We think this is because the cardboard is really smooth so there is not much friction gripping onto the marble to slow it down.

The worst race track was the towel. The towel is really rough and has lots of fibres sticking up. These fibres grip onto the marble creating lots of friction. The marble can't roll very well at all.

Mini Investigations

This week at Science Club Miss Harrison set out a range of mini science investigations for us to have a go at. We had to think about what was happening and come up with an investigation.

This is what we did and found out.

Compression of Substances - Louise
There was the following in syringes - water, salt and air. The hardest to press down was the water and the easiest was the air. Because the end of the syringe was blocked the water needed to go somewhere and it went nowhere so it was the hardest.

Air Takes Up Space - Jack
For this experiment you only need a piece of cardboard, a water tap and a small round container or cup. Fill the cup with water (3/4 full) and put the cardboard over the cup. Tip it upside down. Now let go of the cardboard and hold the cup. The cardboard will stay. This is because the water is pushing down but because the air pushes in all different directions it pushes up and keeps the cardboard on the cup.

Making a rainbow with a Prism - Billy
To make a rainbow with a prism is easy. You get a clear prism and point it at the sun or a light. You see some things in rainbow vision. It is really cool.

Observing a lighted candle - Shikhar
First we lit a candle with a lighter. Then we observed the candle in different ways (eg - blowing, turning upside down and trying to make it go out without blowing or touching it). The bottom of the flame is blue and sometimes white and the top is yellow. This middle is usually orange or red. If you press the very little flame with your fingers it can go out without hurting or burning your fingers. Be careful though. Fire is a very interesting and amazing element.
Air takes up space - Harrison
Put a tissue in a cup and stick it in so it stays at the bottom.
Put the cup with tissues upside down in water.
Take it out.
What happened?

• The tissue is dry. There is still air in the cup so the water can not go in.
• If you put the cup in the water sideways, water will go in.

Air Pressure - Russell
We had 2 syringes and a tube joined onto both of the ends. This experiment worked by air pressure. When you pushed the air out of one tube it makes all the air go into the other tube, making the other tube go up.
Putting a jar over a burning candle - Ella
We lit a candle standing up in a bowl of water. Then we placed a jar over the candle. After the candle burnt up all the oxygen the candle went out and the water rose up into the jar to take the place of the oxygen.

Putting a jar over a candle - Cameron and Bradley
This experiment was to fill a bowl up with water, put a lit candle in it and cover it with a jar. Then we had to see what happened.
The candle starts to die down and the water starts to rise. This happens because there is no oxygen and there is lots of space for the water to come in.

Solar Panel animations

May the force be with you

This week the Year 3 and 4 classes learnt how to use a forcemeter to measure the force it takes to do different jobs.
This picture shows a forcemeter being used to see how much force is needed to do the job of lifting up a bucket of weights.

The forcemeter has a spring inside that is pulled down as force is applied to the object. The force is measured in Newtons (N) which is named after Isaac Newton.

We also tested how much force was need to...

• lift a school bag
• lift a shoe
• lift a cup
• open the door

Next we got to make our own forcemeters which we called Pull-o-meters. We had to be good at using a ruler to measure out each section.

Instead of using a spring our forcemeters use a rubberband. When the load is hung on the hook the rubberband stretches and we can read the scale to find out the amount of force being used.


Next we used our forcemeters to see if lifting, pulling or rolling a weight used the most force.
We found out that lifting used a lot more force that pulling or rolling. Our explanation for this is that when you lift something off the table gravity starts pulling it back down which makes it hard to lift. When you pull or roll something the object is being supported by the table.

Moo Glue

Did you know that you can make glue from milk? Today in science club we found that it can be.

After reading about it in a school journal we discovered that in the past and in different cultures glue is made from lots of things such as plant saps, animal bones and hides, cassava root, bread fruit and other vegetables.

The article also talked about a class who made their own glue from milk. We decided to try it out.

Casein is a protein that is found in milk and was used by ancient Egyptians as a glue for boat building and to weatherproof aeroplanes during WWII. Casein is what makes the moo glue work.

To get the casein you add vinegar to milk which makes the milk separate into solids and liquids. The liquids are called whey and the solids are called curds. The curds are full of the protein called casein.

The vinegar curdles the milk. They whey is drained off to leave the curds behind.

Most people thought the curds looked disgusting but soon they were happy to touch and squeeze them.

The next step involves adding baking soda and hot water to the curds. You have to mush up the curds and stir for a long time to turn the mixture into a glue.

The moo glue still didn't look like it would stick things down so we tested it out. These are some of the pictures we made. We think they look great. And yes, the glue did work (mostly!)

Do heavy objects fall faster than light objects?

This week the Middle syndicate has been learning about Gravity. Gravity is the force that pulls all objects down towards earth. If we did not have gravity we would all be floating around and life would be pretty hard.

Imagine a bowling ball and a soccer ball. They are the same size and shape but the bowling ball is heavier than the soccer ball. If you dropped them both from a high place at the same time which would hit the ground first?

Most of the children in the Middle syndicate thought that the heavier bowling ball would hit the ground first. So to find out we did an investigation.

We tested pairs of objects that were the same size and shape but different weights. We then held them out level and dropped them at the same time. It was hard trying to decide which object hit the ground first or if they landed together.

We recorded our results on a chart.

Overall we found out that the objects fell to the ground at the same time. This is because size and shape affect how objects fall not weight.

Some people thought that if the objects were different sizes they would fall at different speeds. So we tested this using a flat piece of paper and a screwed up piece of paper. The screwed up piece of paper hit the ground first and the flat piece of paper floated down slowly. WHY?

After thinking about this for a while we decided that...

• Objects that are the same size and shape, but different weights, fall at the same speed because they can push through the air.
• If 2 objects are different shapes but the same weight they will fall at different speeds because the air slows bigger objects down.

Science was hard this week but Miss Harrison was impressed with all the good thinking and explaining that the students did!!!! WELL DONE.

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).