Hello, and welcome to this year's global experiment
by the Royal Society of Chemistry.
This year, you will be exposing different materials to sunlight,
and measuring how they block UV light.
Too much UV light can be harmful, especially to your skin.
It can cause sunburn and increase the risk of developing skin cancer.
Here on Earth, our atmosphere filters and protects us from some of this harmful light,
but in space astronauts are at increased risk from UV exposure.
Here's British astronaut Tim Peake to tell us more.
Space can be a really dangerous environment especially when out on a spacewalk.
Without the Earth's atmosphere we'd get really burnt by UV rays from the Sun,
and the temperature would fluctuate from being really hot to really cold.
So it's really important to have the right type of protection.
The experiment is called Starlight and it's really easy to take part.
Your mission is to discover materials which can block UV light using these beads.
Over to Lee Page from the Royal Society of Chemistry,
who is going to show you how to take part in the experiment.
This year's global experiment contains four investigations.
You could choose to take part in one or all of them.
The beads used for this experiment change colour in the Sun,
and then turn back to white indoors.
The amount of colour change you see will depend on where you are in the world,
and what time of year at is,
as both of these affect levels of UV light.
Your school might have access to UV lamps,
which can also be used to change the colour of the beads.
So the equipment you'll be needing to take part in experiment 1 is,
UV colour changing beads,
petri dishes without lids,
a colour chart for reading your results which is available from our website,
a tray for holding the dishes,
and then the materials to be tested.
For 1a, cotton from a t-shirt,
polyester from a sports top,
aluminium foil,
and high density polyethylene plastic which can be cut out from a milk carton.
For 1b, six layers of polystyrene,
polyvinyl chloride using cling film,
and red and yellow cellophane from a craft shop or from sweet wrappers.
In this second investigation, you will find out if liquid coatings can be used to block UV light.
So the equipment you will be needing to take part in experiment 2 is,
UV colour changing beads,
petri dishes with lids,
paint brushes,
measuring cylinders or a beaker to measure 10 and 30 ml,
a teaspoon,
the colour chart for reading your results which is available from our website,
A tray for holding the dishes,
and the materials to be tested which are,
vegetable oil,
pre-prepared black tea,
sunscreen either SPF factor eight or ten,
and tap water.
Scientists have discovered that a chemical called titanium dioxide
is good at blocking UV light.
Because it doesn't dissolve in oil or water,
it is held in a suspension which is a mixture of insoluble particles dispersed evenly in a liquid.
This is what sun creams are - a suspension of titanium dioxide.
In this third investigation, you'll be using sugar as a substitute for titanium dioxide,
and you will determined the particle size for making the best suspension.
So the equipment you'll be needing to take part in experiment 3 is,
transparent disposable cups,
measuring cylinder or beaker to measure 100 ml,
a teaspoon,
stopwatches,
a black marker pen and ruler,
vegetable oil at least 400 ml but it could be more depending on the size of your class,
and then the materials to be tested,
demerara, icing, caster and granulated sugar.
We have made the final experiment an open investigation.
So now it's your turn to make your own UV blocking material.
Tweet us using #globalexperiment to let us know how you got on and what you found out.
Don't forget to upload your data,
post your pictures and view the results on our interactive map.
You can find us by searching for 'Mission: Starlight a global experiment on UV protection'.
And now it's over to you to take part.