Conductors and Insulators

Did you know that electricity can only flow through some materials? Well the clever Year 3 and 4 students do.

They made electrical circuits then put different materials into the circuit to see if the electricity would flow through and light the bulb.

They found out that only metal things would let the electricity through. These have a special name called conductors.

Things made from plastic, glass, wood, paper, fabric, stone, shell and rubber did not let electricity through. These have a special name called insulators.

Changes when a candle burns

This week the Year 5 and 6 classes found out that there are many changes that occur when a candle burns.

So what is produced when a candle burns?

• You sometimes get smoke and soot (which is particles of partly burnt wax)
  
• The wax changes into melted wax.
• Carbon Dioxide and Water are produced from the chemical reaction between the oxygen and the fuel in the flame.

These photos show how we collected soot from the burning candle. We held the tinfoil above the flame, in the top of the flame and near the bottom of the flame.

Miss Harrison challenged us to think about whether these changes were reversible or irreversible (permanent).

This is what we came up with.

Reversible Changes
The only reversible change is the melted wax. When you let the melted wax cool down it turns back into solid wax. You could reshape this wax into a new candle.

Irreversible Changes
The main irreversible change is the water and carbon dioxide. This was formed from the chemical reaction between the fuel and the oxygen and you can't change them back.

Parts of a flower

The Year 5 and 6 Science Club students were the first to use our new microscopes this week.

We brought in a collection of flowers which we first dissected into the different parts.

Then we carefully observed the different parts under the microscope. We were amazed at what we saw.

Parts of a flower - viewed by a microscope on PhotoPeach

Extinguishing a Candle

For a flame to burn it needs 3 things:

• Oxygen
• Fuel
• Heat

This is called the Fire Triangle. If you remove one of these things the flame will be extinguished.

This week the Year 5 and 6 classes investigated what would happen if they put a jar upside down over a candle. They predicted that the flame would go out because all the oxygen would get used up.

The students had to observe the flame carefully to ensure it had gone out before they lifted off the jar. Sometimes the flame was not out and when the jar was lifted oxygen got to the candle and the flame got bigger.

Then they used a range of jar sizes to see if this made a difference to the time the flame burnt for.
After 1 test they found out that the candle in the small jar extinguished before the candle in the large jar. However, they decided to do more testing just in case this was a coincidence.

After more trials they found out that every time the candles in the smaller jars were extinguished the quickest.

Why does this happen? Everyone decided that it was because the biggest jar had the most oxygen inside it so the flame could burn for longer. As the candle burnt it used up the oxygen and gave out carbon dioxide. The carbon dioxide would also help to extinguish the flame.

Super Science Swap

Super Science Swap on PhotoPeach

Super Science Week

Brother and sister explore cabbage magic potion.

This week was National Primary Science week in NZ. At our school we had lots of activities happening including:

• Young Scientist Awards - student brought in science activities and experiments from home to share with their class. It was great to see how many parents got involved in doing science with their children.
• Class Science Quiz - Each syndicate got a science quiz to answer.
• School Science Swap - 1 afternoon all the children in the school got mixed up into groups to work with a different teacher doing a science investigation. Some of the thinks they did were Tie Dyed Milk, Cabbage indicator, water rockets, fizzy rockets, acids and bases, magic raisins, magnets, Flubber, exploring senses, balloon rockets.
• The teachers also had a chance after school to explore lots of different science experiments.

Chemical reactions

Density of salt water - can you make an egg float?

It was a fantastic week and the students were buzzing about all the amazing science they did. Hopefullly we have encouraged some students to do further science study and become scientists when they leave school.

How does a candle burn?

Do you know what happens to make a candle burn? Well the Year 5 and 6 students and teachers thought they did. But we had to change our minds once we learnt what actually happens.

Most of us thought that the wick was burning and that the job of the wax was to hold up the wick and slow down its burning.

But this is actually what happens:

Burning a Candle
By Sarah - Year 6

It all starts with friction between the match head and the strip on the match box. This will make a flame. When you transfer the flame to the candle the heat starts to melt the candle wax. When the wax is melted it forms a dip in the candle, kind of like a crater. A tiny bit of the wax soaks up into the wick and travels upwards. This is called wicking up. When the wax gets to the top of the wick it turns into a gas. When the oxygen and the was gas combine it is a chemical reaction. This keeps the candle burning. The rest of the melted wax drips down the sides of the candle. As the candle wax gets further away from the flame it gets harder and harder until it solidifies. When you blow out the candle a whole lot of smoke rises from the candle letting off all the left over wax gas.

The Burning Candle
By Jesaiah - Year 6

I think the candle burns when the match melts enough was to be sucked up by the wick for the already burning flame on the wick to use as fuel. I think the oxygen in the air acts as a secondary fuel to keep the flame going. I know that when the flame melts the wax, the wax forms a crater-like pool. When the excess was in the pool flows over the edge it solidifies as it gets cooler down the candle. The wax also acts as a structure for the wick. The heat from the flame separates the molecules into a liquid by making them hyperactive. I think that as the molecules move further away they become a gas, which is what goes up the wick and fuels the flame. I know that the flame starts when the gas-wax has made it to the top of the wick then when it hits the oxygen the flame is the result of a chemical reaction.

We also observed the flame carefully and noticed that there are lots of different colours.

Picture from - http://www.educationalelectronicsusa.com/c/fuels-VIII.htm

Investigating Electrical Circuits

This week the Year 3 and 4 students have been investigating how electrical circuits work to make a bulb light up.

The first challenge was to use 1 bulb, 1 battery and 1 wire to make a circuit.

Then a second wire was introduced and students had to work out how to make a circuit, without the bulb touching the battery, using the 2 wires.

Image from: http://www.can-do.com/uci/lessons99/electricity.html

The circuit couldn't have any gaps otherwise the bulb would not light up.

It was quite tricky for the students to figure out what to do but once they worked out that the electricity had to flow around in a circuit from 1 end of the battery, through the bulb and back into the other end of the battery they soon had lights glowing.

Plants need food too

Today in science club we have been learning about nutrition for plants. Plants get nutrition by soaking up water through their roots. The water travels through the veins in the plant up to the leaves.

We set up an experiment to show how water travels in plants We put food colouring in water - 1 red jar and 1 blue jar. Then we split the celery stalk in half up the middle and put 1 end in the blue water and one end in the red water.

We observed that the red water travelled up the stem through the xylem tubes to the veins in the leaves. The blue was only just starting to show.

We also went for a walk to gather different sorts of leaves. We grouped them into categories by looking at their shape, texture, size, veins and edges. We noticed that the veins in leaves look different. Miss Harrison told us that leaves can be grouped by the pattern of their veins.

Palmate leaves - have several main veins that branch out from the base of the leaf.
Pinnate leaves - have 1 main vein running down the leaf.
Parallel vein leaves - have all the veins running in the same direction.

By Caitlin