The rhythmic note tells us how the length of that note compares to other notes, but it does not tell us the exact number of beats for that note.

In the example below, I can tell the following things about the notes:

• The pitch for each note is C (because there is a treble clef).
• The whole note is twice as long as a half note.
• Each half note is half as long as the whole note.

What I do not know from the music above is how many beats the whole note and half notes are worth. For that information we need a time signature. However, before we can understand time signatures we need to understand the musical measure or bar.

## Measure or Bar – Musical Bricks

Music written on the staff is divided into groups of notes called measures or bars (the two terms are used interchangeably). Each measure or bar is divided by a bar line (we don’t use the term “measure line”, which is kind of strange).

Each measure or bar that uses the same time signature has the same number of beats in it. So, you can think of each measure as being like a brick – each piece is the same size.

The music that appeared above has two measures. The first measure contains the whole note, then there is a bar line, then there is a measure with two half notes. We know that these measures are the same length (even though we don’t know how many beats each note receives), because we know that two half notes fit in the same space as one whole note.

Time signatures tell us information about how the beat relates to the measure or bar.

## Time Signatures – Where’s the Beat?

Time signatures appear after the treble clef at the beginning of a piece of music. Unlike the treble clef, the time signature only appears once and does not reappear on each line of music. A time signature only appears within a piece of music if the time signature changes.

### Time Signature Parts

A time signature usually consists of two numbers, one on top of the other. Each number tells you a specific piece of information about the beat as it relates to the measure.

• Top Number = Number of beats in a measure.
• Bottom Number = Represents the type of rhythmic note that gets 1 beat.

The top number can be any positive number that is 1 or greater. Usually the number is small enough to break music down into meaningful and understandable pieces, but theoretically you could have a time signature with 427 beats in a measure (though that would not be very useful!).

The bottom number is trickier. Only certain numbers can be on the bottom of the time signature because the number represents a rhythmic note. Below are the basic valid numbers and the notes that each number represents:

 1 2 4 8 16

### Valid Time Signature Worksheet

For each time signature below, select whether the time signature is valid or not valid. Remember, any number is fine for the top – the bottom number must correlate to a note (which gets 1 beat in that time signature).

 Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid Valid Not Valid