Keith (13) asked a question about thermal papers in cash machines.

Keiths question
More and more places are using thermal paper as a form of receipt paper for customers. With time the information fades. How can one scientifically go about recovering information which may have faded from thermal paper.

Keith, many thanks for the question. I never realised that thermal(heat sensitive) paper was used in so many places and that it is also the basis on which the polaroid camera worked.

Thermal paper is made using a collection of dyes which exist as colourless crystals that become coloured when they interact with an acid.

For those who enjoy their chemistry you might have come across adding a dye called phenolphthalein to an acid solution. The dye changes from colourless to a deep purple.

The applied heat (from the cash register machine) melts a layer in the paper which contains acid crystals. The liquid acid then interacts with the layer below it which contains a colourless crystalline dye which changes colour as the acid interacts with it.  The print then shows. The acid quickly becomes crystalline again.

Over time the print does begin to disappear.

A little investigation.

Obtain an old till receipt which your adults do not want to save. Put it onto an ironing board and with a hot (care) iron, iron it.


To make it more scientific predict what you think might happen before you carry out the experiment. Any ideas, if so you have a hypothesis.  Now find a very old (fading) receipt and using a hair drier blow warm air onto the BACK of the receipt. Again predict.

I think I’ll stop there. Many thanks for the question Keith. Please comment or ask another question.

Braiden (9) asks “What makes a diamond so hard?.

Braiden, my question (before I turn you over to my team) is how do you detect ‘hardness’? Can you create an order of hardness with some common materials?
Lets say:

wood (balsa)
wood (oak)
plastic object
bath sponge
china(cups and saucers)
concrete pathway
metal fork
rock (sandstone)
piece of coal
pencil rubber 
I think that would be an interesting experiment to carry out. You will have to make sure it is a fair test (science is all about fair tests …and questions …and hypotheses and experiment). How will you carry out the experiment? ( a hypothesis is an idea – “I think soft things will float, hard things will sink”)

Now over to my team.

Graphite has a layered structure with weak forces between the layers, This is a weaker structure than the close bonding of the diamond. The carbon atoms like the tetrahedral arrangement of the bonds with other carbon atoms. It is a very strong force.

Hope that makes some sense. If you have questions about the explanation please ask them. If you want to see my ‘hardness’ list go to Science Master Special-Hardness Results

“How did evolution happen?” asks Parm (10)


Parm, it’s all due to some wonderful stuff called DNA however the beginning of life is at the moment attributed to  a simpler chemical called RNA. Somehow 4.5 billion years ago, in a hot chemical quagmire a collection of complex chemical structure was formed which was living, it could reproduce itself. It is thought that this microscopic entity was quite close to the structure of present day bacterias although, it’s make up was completely different. For example it didn’t breathe Oxygen, it is thought that it might have breathed a chemical called Ammonia and it expelled Oxygen. It also, in its structure contained a crude DNA structure.

From this humble beginning all life on Earth evolved dictated by changes in the  DNA molecules that were part of their structure. Plants, Insects, Bacteria, Animals, Fungi, Algae,  all life contains their own DNA molecules which dictate their continued existence.

So for Jeremey, our snail there has been, for some reason, a small change in her/his DNA. The spiral is wrong. Maybe it might be wrong but it might help Jeremy eat a plant that he/she couldn’t eat before and therefore survive and breed more snails like him/her.

Over the millions of years that life has existed on our Earth, now and then, new life , created by old life, experiences a slight change in the DNA, and that means that the new life is slightly different from the life of its parents (plants, animals, fungi ….). If the new life survives, that life will create more new life in it’s form, evolution has taken place.

Hope this makes sense Parm. Any thoughts? Write them in the ‘Leave a Reply’ box.

Questions on electricity were asked by Gavin (10), Tegan (10) and Hayden (9)

Gavin asked “Why does the energy flow through the wires?”

Tegan asked “How does electricity work?”

Hayden asked “How do batteries springs and wires make a complete circuit?”

So how does this compare with a modern day battery. lets have a look and think about Gavins question.

Hayden and Tegan. In the circuit below the  energy flows around the circuit when the switch is closed. Why? What are wires made of? What is special? If the wires were plastic do you think electricity would be able to pass through it? Try and make your own circuits with different materials.

Electricity is linked to the passage of negatively charged electrons. These were very comfortable in the battery until it was connected to a circuit (a circuit is a continuous pathway) and the switch was closed. The circuit gave the electrons (negatively charged) a passage to the positively charged end of the battery. Electricity (electrons) flowed and accompanying the electrons was energy. Look at the Science Master Special on Energy and why not try the Circuit Quiz.


Do not play with mains electricity. It is very dangerous and could kill you.

Tegan (10) asks “How does gravity work?”

Tegan, a very interesting question. This question was asked some time ago and this is what my team said.

In the 17th Century Newton and another scientist called Hooke did some great observations and experiments on falling objects and proposed that gravity was an attraction between any two masses AND the attraction was dependant on the size of the masses involved.

For example you are attracted by the Earth and the Earth is attracted by you BUT your attraction is so much smaller than that of the Earth it does not affect the motion of the Earth. The attraction between you and the Earth is also dependant upon how far away you are from the Earth. The Moon is attracted by the Earth and the Earth is attracted by the Moon. They are both big bodies so gravity does affect the way they move with respect to each other and this dictates how the Moon orbits the Earth.

Some scientists including Einstein have put forward ideas on how gravity operates but even these are being challenged. There a lots of things which are still unanswered. The questions just have to be asked. Thank you for asking it.

Brandon S (10) asked “What kinds of alligators are there?

Nice question Brandon. Alligators and Crocodiles belong to the same family called the Crocodilians.

In a question from Kaia my team introduced the idea of ‘species’ and  said that, for example, there are 20,000 species of butterfly which means there are 20,000 different kinds of butterfly. There are however only two different types (species) of alligator – the American Alligator and the Chinese Alligator. Like butterflies they are almost identical the only difference with the alligators is their size.

There is a lot of work that has gone on by scientists to catalogue animals/insects/plants and other living things. For example you are in the family Sapiens and the Species Homo.

Brandon a question for you. Can you spot the differences  between a crocodile and an alligator?  They are in the same family. Try and let me know.

Thank you for your question.

“How many living things are on Earth?” asks Kaia (8)

Thanks team.

If you want a definition of ‘living’please click on the link.

The species  butterfly has  20,000 of the 1 million species in the insect group. At any one time there must be thousands of living Cabbage White butterflies flying around so you have 20,000 different types of butterfly flying around and maybe there are 50,000 of each type living at any one time.  Help. I must admit the calculations are frightening so i cheated and looked at the work of other scientists who say that there are  8 million species and each species has millions of living specimens. 

The homo species (us) has 9 billion living specimens, I suspect the ant population is considerably bigger than that so in answer to your question …. and then think of the number of plants  ….and then the number of bacteria …..there is no believable answer. However somebody has tried and they had difficulty putting all the numbers on their sheet of paper. Sorry Kaia.

If there are other questions which you may have thought of then please fill in the Reply box below or ask another question.  

Revised 17/102017  Numbers on image changed and text rewritten.

Lexi (9) and Jaeda (9) and Cadence(8) asked a question on “Minerals”

Lexi, a nice question, a lot of elements are found within the form of a mineral. I shall let my team introduce the answer to this question.

Jaeda. You asked a question on crystals and why are they so expensive. This is not  a science question however most crystals are minerals so this question is also addressed to you.

Cadence . You asked about talc, which is a mineral.

All minerals are found in rocks. It is thought that some are created by the magma (lava) from volcanoes while other were formed in the Earth’s mantle and have reached the surface through earthquake activity. The minerals created from volcanoes have smaller crystals (probably cooled faster), minerals created more slowly in the mantle consist of bigger crystals. All of the minerals are created by a chemical reaction.

A lot of minerals are mined, dug from underground shafts. A lot of minerals have the elements Silicon and  Oxygen in them.Talc is a mineral of the elements Magnesium, Silicon and Oxygen and is mainly found in Japan and the United States.

Have fun and watch this video on minerals.

Thank you Lexi, Jaeda and Cadence. If you want to comment on this post please feel free to do so in the Reply box below. Or why not ask another question.

Could the Earth’s core be hotter than the Sun? asks Brooke (9)

Brooke. When earthquakes occur ( For how they occur see this question) you get a seismic wave travelling outwards from where it occurred. Imagine an explosion, a rock cracking a noise bigger than anything  you have experienced.  It would create the biggest sound ever, shake the ground more than it has ever been shaken and send a signal to the rest of the Earth that the earthquake had happened. It is this seismic wave of spreading energy that has helped scientists discover the structure of the inner Earth. The waves spreads out in all directions and some of them pass through the centre of the Earth. If you look at the waves on the other side of the Earth you can examine them and find out what they have travelled through.

It is now thought that the temperature of the inner core is close to 7000 degrees K (Kelvin). It is however not a liquid , because of the pressure of all the stuff on top of it. It is therefore a solid iron core at about 7000 degrees K…which is close to the outer temperature of the Sun.

(0 degrees K=273 degrees Centigrade so 100 degrees Centigrade = 373 degrees K )