A semitone is the distance between any two adjacent notes on the piano. For example the distance C to C# or D# to E.
However, you cannot just describe it as the distance between a black note and a white note because the distance B to C (and E to F) is also a semitone because those notes are adjacent to each other.
A tone is 2 semitones. Or, you could say, a semitone is half a tone - so when your director says "take it up a half", she is referring to "half a tone" (a semitone). That means that every note in the music is sung one semitone higher than written.
This information under this heading is a bit more technical and you don't really need this to sing songs - it is just some background information in case you are interested. So if you find it too confusing, feel free to skip to the next heading!
The distance between the notes in a Major scale are "Tone, tone, semitone, tone, tone, tone, semitone"
(You may need to chant that to yourself a few times. The tones are in groups of 2 and then 3 - just like the black notes on a keyboard.)
C Major doesn't have any flats or sharps in it. It is only the white keys on the keyboard. Start at C on the keyboard below and count "tone, tone, semitone, tone, tone, tone, semitone" and see that it is just white keys (no flats or sharps) - remember a semitone is the distance between two adjacent notes and a tone is two semitones.
You can work out what the sharps and flats are for any major scale using this method. You can see the sharps for the scale of D major by starting on D and counting "tone, tone, semitone, tone, tone, tone, semitone". In this case D major has F# and C#. Try it with another note - start anywhere you like.
You don't need to do anything complicated like the paragraph above to work out a key signature with sharps. The order of the sharps is the reverse order of the flats (remember that the flats were "BEADs Give Choruses Fun")
For sharps the order is FCGDAEB
Remember this with:
Father Christmas Gets Drunk And Eats Bananas
(Note for US Visitors: Father Christmas = Santa Claus)
So if there is only one sharp, it will be a F#
If there are two sharps they will be F# and C#
If there are three sharps they will be F#, C# and G# and so on....
Unfortunately the rule for calculating the pitch is different for sharps than it was for flats - but luckily it is also pretty easy. (I've reviewed the rule for flats so you can compare them.)
For key signatures with flats, look at the second to last flat and that is the key.
For key signatures with sharps, look at the last sharp and go up one semitone and that is the key.
So if there are two sharps, then the sharps are F# and C#. Since D is a semitone above the last sharp, it is the key of D major and D is the pitch played at the start of the song.
(Hint: It is actually the next letter in the alphabet up from the last sharp until you get to 6 sharps and you don't often see that many sharps in a key signature!)
A quick game to test out your new found skills
Little known fact: The common housefly hums in the key of F.