When I write for my IELTS teacher, she always says that I should not use ‘and’ and ‘but’ at the beginning of a sentence.  Why?
(Alejandra, Colombia)

Thank-you very much for this question, Alejandra, as this is one aspect of written English that is very difficult to get correct.  Let’s have a look at this in a little detail.

Firstly, we need to look at the function of these words.

We all know that ‘and’ links two or more equal ideas together in one sentence, for example:
I like pop and rock music.
Here, as you can see, the two ideas are pop music and rock music, which are joined in one sentence by ‘and’.  ‘And’ is a co-ordinating conjunction – a joining word.  The two other co-ordinating conjunctions are but and or.  Usually with these words, they have to go in the middle of a sentence and not at the beginning.  This is where these words would seem wrong at the start of a sentence.  In formal writing, especially for the IELTS exam, these words should not be used in this position.  There are alternatives to use, such as;

‘and’ – In addition, Moreover, Furthermore,
‘but’ – However, Nevertheless, Nonetheless,
‘or’ – Alternatively, Otherwise

These alternative words are not conjunctions, but are linking adverbs.  These can generally go at the beginning of the sentence – they also differ in the fact that they need to be used to link two sentences, not ideas.  Look at this;

He studied hard for the exam.  He failed it.
He studied hard for the exam, but he failed it.
He studied hard for the exam.  However, he failed it.

Another way of linking ideas is subordinating conjunctions.  These are words that join ideas together in one sentence, but are dependent on the main clause – they cannot stand alone in one sentence.  Take for example, synonyms for ‘but’ –

He studied hard for the exam, but he failed it.
He studied hard for the exam, although he failed it.
Although he studied hard for the exam, he failed it.

You can see here that ‘although’ links the two clauses together in one sentence, and it can go either at the beginning of the sentence, or in the middle.  Other such subordinating conjunctions include even though, while and whereas.

Practice
Can you link these ideas together, using the word in brackets – remember, you might need to use one or two sentences!

1 – I believe that people work too hard nowadays.  I believe that they socialise too much.  (In addition).
2 – The princess is very intelligent.  She has a lot to learn.  (but).
3 – The princess is very intelligent.  She has a lot to learn.  (Nevertheless).
4 – I like U2.  I don’t want to go to their concert.  (although).
5 – Mary works hard.  Jonathon doesn’t work hard.  (whereas).