If you haven’t already started to write things down on a computer, or other electronic device, then you are going to soon. You are going to be doing it a lot at school and then later when you go to work. Grown ups are using paper and pens less and less these days.

You can and should learn a number of skills to make writing on electronic devices simpler and better. In my opinion one of the most important of these is to learn how to touch-type; to write quickly without making mistakes using all ten fingers of both hands across the whole keyboard. With practice it is possible to be able to write at almost the same speed as it does to think. This is very difficult to do when using a pen and paper, and my handwriting looks like a drunk spider has escaped across my page from an inkwell when I try to write at anything approaching this speed. We will talk about learning to touch-type another time.

In the same way that there are different types of real paper, there are also different types of electronic paper. Knowing which kind to use is another useful trick, so that is what I am going to talk to you about today. Real paper can be shaped differently, have different thicknesses, and be of different colours. It may respond in unusual ways to some types of pen or pencil. Writing on electronic devices doesn’t involve paper, of course, but there is a choice of what software programme to use. Each allow you to write words in your alphabet of choice but they get to that result by means that are not the same. They record electronic writing in different file formats. You could think of files as electronic paper. Often these sheets of electronic paper are not readable by any other software. This is a problem if you want to use more than one device - such as a computer, a phone, a tablet, or a web-based word processor - to write on the same bit of electronic paper. Imagine only being able to use one type of pen on a piece of paper! Worse than this, the software applications you use today might not necessarily be around in five, ten or fifteen years from now. The homework you finish this year might not be able to be read again by the time you have left school and may be lost forever. OK maybe that’s not so terrible, but you get the idea; if you are bothering to keep your electronic documents then you want them to be readable in the distant future.

So my suggestion to avoid these problems would be to use text files. This type of electronic paper is just about the smallest and simplest type you could use. You can recognise text files because they have a .txt at the end of their name. Text files only include information about the letters, numbers and other symbols that you can see and so they only take up a small space on your device’s filing system or memory. Small is good when it concerns disk space and sharing files. How small are they? Well the text file I created writing this blog post was just 8 kilobytes. The same amount of words in a word processor software file was 459 kilobytes. The text file was 57 times smaller! Most applications and software can open text files because they are so simple. This makes it possible to use multiple devices to write on the same sheet of electronic paper, and it means that they will be readable a long way into the future by newer electronic devices. For those reasons you want to use this type of file above all others if you can.

The downside of using text files as digital notepaper is that they can’t do a lot. They are text and nothing else. All the extra stuff that people do with their writing using their word processors can’t be recorded in a text file. For example, making some text bold or writing a list of items with those items automatically numbered. But then a few years ago something changed. You couldn’t do those things with text files until something called markdown came along and changed things for the better.
Markdown is a way of writing that uses regular text file-friendly characters to put back in the formatting and other stuff that you can’t normally have in plain text files. It uses special marks amongst normal writing that a computer programme understands as being instructions about what to do with parts of the text. These marks don’t get in the way and still allow the text to be read easily by humans. It is very simple to use and, because you are going to use text files as your electronic paper of choice for all the reasons I’ve suggested you should, you should learn some basic markdown to help yourself in the years to come.

A simple example of how to use markdown would be to show you how to make a small amount of text appear bold. You do this by putting two asterisks ** at the beginning of the text selection and then another two asterisks at the end. So if I want to make these words bold, then I put two asterisks either side like this: **these words**. Any computer writing program that understand markdown - some don’t but many new ones do - will know that this is the instruction to make these words go bold. Instead of two asterisks you could use two underscore characters __ to do the same thing.
Another example of markdown is creating bulleted lists. If you create a list with asterisks, dashes or plus signs for every point, a markdown-friendly software programme will turn that into a proper bulleted list like this:

• Item one
• Item two
• Item three

I made the above list by simply typing this:

- Item one
- Item two
- Item three

The software I am using automatically turned the dashes into round bullet points.

There are lots more things that markdown can do. Take a look at the website of John Gruber, who invented it. If you want more then another clever chap created more types of special mark that can be used by lots of apps and programmes to create tables, citations, and other things you might need when you are a bit older and maybe doing a college degree. His name is Fletcher Penney and his website about his special marks, called MultiMarkdown, can be found here.

That is enough information for you to know the basics of what markdown is and know where to find out more about it. I can’t teach you much more other than to say that the best way to learn the special signs that make text files more useful is to start using them yourself and play with them to see what they can do.

The last thing I will do is to mention some software that can understand markdown in text files. I use a Mac and my favourite markdown editor is Byword. It also has an iOS application for iPads and iPhones. IA Writer and Writeroom do similar things I’m told. I heard that WriteMonkey is a solid bit of software for writing markdown on the PC but I’ve not used it myself. The Day One journal/diary Mac software - which is the best way I’ve seen to write an electronic diary, by the way - and iOS app understands markdown too. If you want to use a web-based writer then I’ve successfully used Dillinger although the saving of files somewhere such as in my dropbox folder was a bit tricky to understand at first. There are other markdown-understanding web word processors around I’m sure.

I am very glad that I learned how to use markdown with plain text files this year, and I’m sure that I will be using this way of writing on electronic devices for many years to come. I’m sure if you investigate it and get the hang of it that you will be doing the same too.

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This blog post was written for my nephew, Eshan, who asked me to write about this subject.

You wanted me to write something for you about computers and so here is a blog post about them. This post comes after one about secret codes for a reason: computers are here because of secret codes and now they are everywhere. No matter what job they do, or where they are, all computers have a lot in common with each other.

The word computer is not modern. It was first used 400 years ago to describe a person who did maths. Someone who did calculations - or computations as they can be called - was a computer. Today we use the same word to talk about machines that do the same things with numbers.

A computer is a machine that can do maths of different kinds. It can do different sums, depending upon what it is told to do. The sums it is asked to do are called a program, and the person telling it what to do is the programmer. Programmers tell computers what to do by writing down the instructions in a special language that the computer understands.

The difference between a computer and a calculator is that a calculator needs someone to put in the numbers and read the results. A computer doesn’t need an operator. Once it has a program to follow it can get on with it alone without any help.

The idea of a machine that could do maths was thought of a long time ago, in the 1600s, but the first proper ones were made in World War II to do maths to break Germany’s powerful secret codes that were themselves created by machines. The first computers were not very powerful and were enormous: sometimes as big as rooms. At first they were hand-operated mechanical machines, but very soon after electric computers were invented. Ever since then computers have become more powerful and smaller year by year. Nowadays they are everywhere. In phones, in cars, in planes and even in watches. They are still getting smaller and more powerful.

No matter how tiny or fast they are, all computers are made up of the following parts:

The Number Factory

The most important bit of a computer is the number factory where the maths happens. The very first computer machines could only do one set of sums. To change what they could do meant changing the wiring of the machine, which was difficult and took a long time. So someone invented a programmable computer that could do different sums depending upon what instructions it was given. At first these instructions were short and simple but now they can be very long and complicated. For example, the maths needed to make a web browser surf the internet, or to play an audio file, as you are doing now, can be many millions of instructions. This is OK, because modern computers can carry out billions of instructions per second! The part of the computer that does all this work - the number factory - is known as the central processing unit or CPU.

The Memory

A computer reads instructions just like you are reading this blog post, from start to finish, but some instructions are more complicated. They could be like this:

From this line go back to the second paragraph of this blog post, read the first line, and then come straight back to this line without reading anything else inbetween and then carry on reading from here.

Or this:

Carry on reading, but do not read the last paragraph of this blog post if the time is after 3pm in the afternoon and before 10pm at night.

To do this jumping back and forth kind of reading you need a memory. To follow the first instruction I wrote above you would need to remember what I told you to do and then remember how to get back to the line of writing you started from. Every computer is the same, and so needs a memory.

A Language

Every different type of number factory has its own special language called a machine code. So the computer in a mobile phone can’t understand the language of a computer in a car, for example. Instead of having words made of letters, computers have words made of numbers. It would be very difficult and very time-consuming for humans to write instructions in machine code, and so instead they write the instructions in an easier to understand programming language. This is then translated into machine code by an translating program that programmers use called a compiler.

Parts to Put Information In

There has to be a way of giving the computer instructions. Information has to go in somehow to program it. There are lots of ways to do this with modern computers. A home computer will often have a keyboard and a mouse. Games console have gamepads. In a car there will be sensors, such as ones measuring how much air is in the tyres.

Parts to Get Information Out

There is little point in making a computer do a calculation if it doesn’t do something with the results for a purpose. So there will be parts of a computer to do something after it has followed the instructions in the program. You might be able to see information on a display screen, such as on a home computer or smart phone. A printer will write something onto paper. The computer could be connected to speakers so you may hear something after it does its work.

Computers are everywhere. The obvious ones are the personal computers and laptops in our homes, or the smart phones or tablet devices we carry around with us. The less obvious ones are those in modern cars, in shop tills, and now in wristwatches.

The reason computers are everywhere is because they are so useful. We can do incredibly hard mathematics with them, such as programming them to fly rockets in space, or to predict what the weather is going to be tomorrow or to work out how many miles a car has left before it runs out of petrol. We can play complicated games and make imaginary worlds on home computers and gaming consoles. We can talk to each other on phones, or over Skype; write letters and then print them out; or post them up on the internet for people to read.

I hope that gives you a helpful introduction to how computers work. We can talk more about them another time.

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Why Do People Need Secret Codes?

Imagine you have a secret you want to tell your best friend, but nobody else. Perhaps last night you discovered you could fly. If everyone found out they would ask you lots of boring questions like, “What does my house look like from the sky?”, and your Dad would want your help cleaning out the gutters of the house. Yuk. Stuff like that.

If you were alone with your best friend in the same room then sharing the secret would be easy to do, but if he or she was somewhere else, or you were not alone, that would be more tricky. Somehow you would need to send the secret to that person in a way that only they could understand it. How could you do that?

You could make up your own special language that only the two of you could understand, but creating a brand new language would be very hard work and would take up a lot of time and practice; years probably. All that effort just in case one day you need to share a secret. That’s quite extreme.

How Secret Codes Work

A simpler way would be to use your normal language, but wrap up the message in a secret code. That would be a bit like sending a letter in a locked envelope. If you gave your best friend, and only your best friend, the key to unlock the envelope before you sent the message, then only he or she would be able to open it and know its true meaning. This is how all secret codes work.

I’m going to teach you a few new words. A secret code can also be called a cipher. Its pronounced ‘si-fer’. The original message in your language is called the plaintext. The message written in secret code is called the ciphertext. The act of turning a message into the coded message is called encryption; you encrypt the message. The act of turning the coded message back into the normal message is called decryption; you decrypt the coded message. The exact way encryption and decryption works is called the key for that particular code.

An Example: The Caesar Cipher

The best way to explain how this works is to show you. Let’s use a real secret code that was used a long time ago. It’s called the Caesar cipher, and is named after the famous Roman general, Julius Caesar, who used this way of encrypting his important letters, such as commands to his soldiers on the battlefield, so that his enemy wouldn’t understand them if they found them.

Let’s imagine that you want to send your friend the message “I can fly.”. The way this particular cipher works is that it swaps each letter in the message to a different letter in the alphabet to make it look like nonsense. The Caesar cipher transforms each letter into the letter 3 places further up the alphabet. They key to this code is +3. Other types of cipher transform letters in different ways to do the same thing. Our plaintext message is icanfly when written with no spaces inbetween. Now let’s encrypt the message. The table below shows how that transformation works for each letter of the alphabet using the Caesar cipher:

After encryption the message reads “MFDQIOB”.  That doesn’t mean anything to most people, does it? But to your friend, who knows what you have done, it does. When they receive the message they know they need to do the opposite transformation to be able to read it. In this case, they will need to change each letter in the ciphertext to the letter 3 places before it in the alphabet and then put the gaps back in sensible places so that the message makes sense:

So your friend will turn MFDQIOB into icanfly and then understand that you have cracked the ability to fly.

There are lots of ways of turning plaintext into ciphertext and back again. The history of secret codes is interesting on its own, but one of the most wonderful things about it is that nearly 80 years ago some British people who were trying to break some secret codes that they didn’t have the keys for created the World’s first computers to help them. I’ll tell you more about that in my next blog post.

EBHEBH

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The stars on a clear night look as if each are the same distance away from us. Some appear bright and big, and some small and dim. It looks like a curved picture has been hung up across the sky. Because we are small creatures living on a little rocky planet that circles around a normal sized star we don’t find it easy to understand how big the Universe really is. Really, the night sky is our view of the Universe, and it has incredible depth. Some stars are close and some are very far away, and they can be very different sizes and brightnesses.

At this time of year an easy-to-see constellation is high in the sky just after the sun sets. It is called Orion, sometimes known as Orion the Hunter, and if you look at the picture at the top of this post you might see why. You have to use your imagination a bit - you do to see any of the pictures people say you can see in the night sky - but it can look a bit like a someone holding a bow with their other arm raised high behind as if pulling the bowstring or holding a club. There are three equally bright stars in the middle that might be the hunter’s belt.

A little bit down and to the left of this group of stars is a very bright star that you should see easily unless there is a cloud or a tree or a building in the way. This star is called Sirius and the ancient Egyptians used to think it very important because, when it rose on a certain summer morning after being behind the Sun for 70 days, it meant that the river Nile was about to flood and water the desert. We still think it important for a more simple reason; it is the brightest star in the sky.

Both the Orion group of stars and bright Sirius are almost directly south of wherever you are, if you look for them between 7pm and 9pm in the evening at this time of year, so I thought now would be a good time to point them out to you. I hope you get a clear sky one evening this month so you can see them for yourself before bedtime.

Among these beautiful lights there are some giant stars. Which do you think is the biggest star in this part of the sky? If I didn’t know better I would say Sirius, because it is the brightest, and if all stars were the same distance away from us that would be true but they aren’t.

Sirius is eight and a half light years away from us. That is a distance that the human brain can’t really imagine: how far a torch beam would have traveled eight and a half years after it left the torch. Even so, this is one of our Sun’s neighbours; the seventh closest star. It is bigger and brighter than our Sun. If we could swap them around and make Sirius our Sun it would be about 26 times as bright. This is because it is bigger in size, and also because it is burning hotter: so it sends out more light. But in this part of the night sky there are even bigger and brighter stars than this.

There is a star to the right side and above Orion’s bow. It belongs to a neighbouring constellation, Taurus the Bull. Our hunter is chasing this bull. If you spend some time looking at the sky you may notice that this star looks a bit red rather than white or blue. It is a giant red star called Aldebaran and is about 67 light years away; so nearly eight times further away than Sirius. Although it doesn’t look as bright as Sirius it is 16 times brighter and much bigger. Let me explain what I mean by that. If you hold a small torch close to your eye it will be brighter than the lightbulb hanging from the ceiling but only because it is closer to your eye. Sirius appears brighter than Aldebaran for the same reason. If you were able to fly close to huge Aldebaran the red light would be as bright as 425 suns, but it is not the brightest star out there in that part of the sky.

The bright white-blue star at the foot of Orion is called Rigel. It is twice as far away as Aldebaran - 860 light years - but still appears just as bright. It is a huge blue giant and as bright as 85,000 suns if you could get close enough to see for yourself! Just as bright as this but a bit closer at 560 light years away is the red giant Betelguese. It is the same distance above and to the left of the three belt stars of Orion as Rigel is below and to the right. If your eyes get used to the dark you may be able to see the difference in colour between red Betelguese and blue Rigel. Huge and amazing though these giant stars are, they are not the brightest in Orion.

The three lovely belt stars are easy to find in a clear sky but they aren’t the brightest to our eyes. The middle of the three, Alnilam, is twice as far away as Rigel - 1340 light years - and if you could get close enough you would see that it is as bright as 375,000 suns. It is a blue supergiant, which is a pretty good name for a star that is 20 times the size as our Sun and five times hotter.
I hope I haven’t clouded your head with numbers. If you can turn these numbers into a picture you will start to see how three-dimensional the night sky truly is and how stars aren’t necessarily like their neighbours.

Here is a drawing I have made to show you how far away these five stars are from us compared to each other:

I’ve also made another drawing to show you how big they are compared to each other:

A few weeks ago I found this old but good video on YouTube about the sizes of things in space. Some of the giants I have shown you are in it and some even bigger ones too. I hope this helps you imagine how big the Sun, Sirius, Rigel and Aldebaran are compared to each other:

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