Number 3: The flaming orange

Since we've already got our candle out I thought we'd make more use of it.

You'll need:

• A candle.
• Some matches or a lighter.
• A thick skinned orange (navel oranges work well) or other citrus fruit.
• A knife.

Safety:
We're using fire again so keep that adult close by and you'd best get them to peel your orange as well.

What to do.
1) Start by peeling the orange. Keep the peel handy, eat the orange.
2) Hold some peel between your fingers and thumb with the orange side facing away from you.
3) Squeeze the peel, you should see little droplets spraying out of it.
4) Light the candle and dim the lights.
5) Now get another piece of peel and squeeze it towards the candle flame.
6) You should see something like this.

Cool ain't it!

What's going on?
Citrus fruit peel is full of an oil called limonene, which is what the droplets are made of. In fact its this stuff that makes the peel smell so nice. Limonene is really flammable, so when you squeeze it into the flame is catches fire and produces that fab flamethrower effect.

Hold on a mo I hear you yell. How come lemon and orange peel smell different if they contain the same chemical that makes them smell? Good question. We it turns out that the limonene in oranges is the mirror image of limonene in lemons and even though they have exactly the same chemical formula our noses can tell the difference.

Number 2: The jumping flame trick

This makes a great 'magic' trick for birthday parties or boring dinner parties for that matter.

What you need:

• A candle
• Some matches

Safety:
Flames are involved so best make sure there is a sober adult present.

What to do.
1) Light the candle and let it burn for a minute or until the wick is surrounded by a puddle of liquid wax.
2) Blow out the candle.
3) Hold a lit match in the candle's smoke a couple of centimetres above the wick.
4) Bingo, the candle should suddenly reignite.

What's going on?
To set things alight you need oxygen (which comes from the air), an ignition source (the flaming wick) and some fuel (the paraffin wax in the candle). The flame melts the wax which is then drawn up the wick and so provides the flame with a ready source of fuel. When you blow the candle out the wick contains some of this liquid wax and the glowing end of the wick heats the wax still further so that it vaporises (to a gas) and drifts off with the smoke. The gaseous wax is flammable so when you put a match in the smoke you ignite the gas, the flame travels down the smoke trail and then reignites the wick. It all happens too fast for you to see so it looks like the candle spontaneously relights when you hold a match above it.

Citizen science: The protein folding problem

The fold.it and fold@home projects are a fab way to get involved in some really BIG science. And the best thing about it is that all you have to do is play a computer game or just install a bit of software on your PC!

http://fold.it/portal/
http://folding.stanford.edu/

Basically both these projects are working on something called the protein folding problem. Proteins are the molecular machines that are involved in just about every conceivable job in your body. They replicate  DNA, hold your joints together, fight infect, you name it they do it.

Not only are proteins amazingly useful but they are also fabulously beautiful structures. These two images show the structure of two very different proteins. The first one is called catalase and it mops up harmful hydrogen peroxide that your cells make as a waste product of metabolism. The one below is called rhodopsin and it is produced in the cells on the retinal at the back of your eyes, its sensitive to light and acts like the film in a camera.

The thing is that proteins are all made up of just 20 different building blocks called amino acids. These amino acids fit together to form a long chain, just like beads on a string. For a protein to do its job this string of amino acids needs to fold up in exactly the right way. The astonishing thing is that there are more ways that a protein can fold than there are atoms in the Universe. But somehow proteins 'know' which 'fold' is correct and how to get there in fractions of a second. Its sort of like throwing all the pieces of a complex robot into the air and expecting them to land as a fully functioning machine.

So how do proteins do it? Well the short answer is we really don't know. Despite a massive amount of computer power we still aren't very good at predicting how proteins fold. And thats were you come in. Because the fold@home project lets you run protein folding simulations on your desktop PC or  Playstation. You might think that this won't make much of a difference, but over 5 million home computers all round the world are running fold@home and  together they make up the second most powerful computer on the planet.

The fold.it game takes another tack. The idea here is to get people to play with proteins and get them to fold. Then scientists look at the strategies that gamers used. They then take this information and input it into computer algorithms. Nice idea and really quite successful, they and their gamers have published their findings in the most prodigious scientific journals (http://www.cs.washington.edu/homes/zoran/NSMBfoldit-2011.pdf).

Number 1: The Film Canister Rocket!

We're going to start with one of my favourites; the great film canister rocket!

You'll need:

• 1 film canister (you can still get them, try Jessops or anywhere else where they still develop film). The ones white ones with the white lids work best.
• Lemon juice or vinegar (lemon juice smells nicer, but vinegar works just as well)
• Bicarbonate of Soda 
• A teaspoon
• Some toilet roll
• SAFETY SPECS!

Safety:

Wear those safety specs and this one is best done with adult supervision. 

What to do.
1) Take everything you need outside
2) Put the safety specs on and keep them on until the end.
3 Take the canister and pour in the lemon juice or vinegar until you have about 1cm worth in the bottom.

4) Take a square of toilet tissue and put it on top of the canister, gently push the tissue into the canister so that you have a small pocket in the top. Make sure the tissue doesn't touch the liquid in the bottom.

5) Next spoon in 1 teaspoons worth of bicarbonate of soda. Then snap the lid tightly back on the canister. 

6) Now you have to be quick! Grasp the canister (keep it at arms length).  Turn the canister over and give it one or two good shakes. Put it, lid down, on a surface. 

7) Stand back and watch it fly!

Whats going on?

The bicarbonate of soda reacts with the acid in the vinegar or lemon juice to produce carbon dioxide gas (and water). As more gas is made the pressure inside the canister builds up, eventually the pressure gets too much and the lid pops off. The gas escapes out and pushes the canister up. 

This is exactly the way that real rockets work (except you can't get to the moon with bicarb and vinegar as a fuel). But your rocket does follow something called 'Newton's third law of motion', which states that "every action has an equal an opposite reaction". In this case this means that the action of the gas escaping from the canister has an opposite reaction which pushes the canister into the air.

Science @ home

There's loads of great science experiments you can do at home. You don't need loads of academic knowledge or fancy bits of equipment. You can find everything you need for fun experiments with the contents of your kitchen cupboards or tool shed.

But lets not just tinker with bits and bobs, because I'm also going to get stuck into the BIG science projects that anyone can get involved in.