Data is information Data handling is when we

Data is information Data handling is when we organise, display and try to understand information.

Some children wanted to find out about the length of songs. They wanted to know how long most songs were. They listened to some songs and timed how long each one lasted

Here are their results: • • 3 min 20 seconds 2 min 58 seconds 3 min 12 seconds 1 min 59 seconds 4 min 03 seconds 2 min 15 seconds 3 min 32 seconds • • 3 min 37 seconds 3 min 58 seconds 1 min 45 seconds 3 min 0 seconds 3 min 13 seconds 2 min 35 seconds 3 min 17 seconds

Not very easy to understand is it? Let’s turn it into a graph. . .

Graph showing how many songs there were of each length 1. 2 Oh dear. . That wasn’t much help 1 Number of songs 0. 8 0. 6 0. 4 0. 2 0 1. 45 1. 59 2. 15 2. 35 2. 58 3. 00 3. 12 3. 13 Length (in minutes) 3. 17 3. 20 3. 32 3. 37 3. 58 4. 03

Every song is different. . . So how can we find out what sort of length is most common? We can group the data We’ll start by sorting it into a tally chart

• • • • 3 min 20 seconds 2 min 58 seconds 3 min 12 seconds 1 min 59 seconds 4 min 03 seconds 2 min 15 seconds 3 min 32 seconds 3 min 37 seconds 3 min 58 seconds 1 min 45 seconds 3 min 0 seconds 3 min 13 seconds 2 min 35 seconds 3 min 17 seconds Song length 1 min 30 sec to 1 min 59 sec 2 min 0 sec to 2 min 29 sec 2 min 30 sec to 2 min 59 sec 3 min 0 sec to 3 min 29 sec 3 min 30 sec to 3 min 59 sec 4 min 0 sec to 4 min 29 sec 4 min 30 sec to 4 min 59 sec Number of songs

Remember how we tally in fives: So how many does this tally show? 18

Right, let’s get back to that tally chart. . . and change it into a frequency table

Tally chart Song length Number of songs Frequency table Song length Number of songs 1 min 30 sec to 1 min 59 sec 2 2 min 0 sec to 2 min 29 sec 1 2 min 30 sec to 2 min 59 sec 2 3 min 0 sec to 3 min 29 sec 5 3 min 30 sec to 3 min 59 sec 3 4 min 0 sec to 4 min 29 sec 1 4 min 30 sec to 4 min 59 sec

Well, that bit was easy! Now let’s display the information in a pictogram

We’re going to use one CD to stand for 2 songs, like this: Song length Number of songs 1 min 30 sec to 1 min 59 sec 2 2 min 0 sec to 2 min 29 sec 1 2 min 30 sec to 2 min 59 sec 2 3 min 0 sec to 3 min 29 sec 5 3 min 30 sec to 3 min 59 sec 3 4 min 0 sec to 4 min 29 sec 1

Now we can use those symbols to make a pictogram 1 min 30 sec to 1 min 59 sec Song length 2 min 0 sec to 2 min 29 sec 2 min 30 sec to 2 min 59 sec 3 min 0 sec to 3 min 29 sec What else do we need? 3 min 30 sec to 3 min 59 sec 4 min 0 sec to 4 min 29 sec Number of songs = 2 songs

4 Song length 4 min 0 to 4 min 29 3 min 30 to 3 min 59 3 min 0 to 3 min 29 2 min 30 to 2 min 59 2 2 min to 2 min 29 mode 6 1 min 30 to 1 min 59 3 min This is to the called 3 min 29 sec 8 Number of songs We can Which show lengththe of song is the same most information common? in a graph:

Song length 4 min 0 to 4 min 29 3 min 30 to 3 min 59 3 min 0 to 3 min 29 2 min 30 to 2 min 59 2 min to 2 min 29 1 min 30 to 1 min 59 True Number of songs True or false? Most songs are between 3 and 4 minutes long. 8 6 4 2

Grouping data When you group data, you have to make all the groups equal. In this example, all the groups were 30 seconds long. The same rule applies to any grouped data. If we were grouping tables test scores, we could use: 0 -10, 11 -20, 21 -30, 31 -40 and so on.

What have we learned? • • • How to group data How to make a tally chart How to make a frequency table How to make a pictogram How to make a graph (bar chart)