2. 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
3. • 3min 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
Here are their results:
• 3min 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
4. Not very easy to understand is it?Not very easy to understand is it?
Let’s turn it into a graph...
5. Graph showing how many songs there
were of each length
Length (in minutes)
Numberofsongs
Oh dear.... That
wasn’t much help
6. Every song is different...
So how can we find out what sort of
length is most common?
We’ll start by sorting it into a
tally chart
We can group the data
7. Song length Number of songs
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
• 3min 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
• 3min 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
8. Remember how we tally in fives:
So how many does this tally show?
1818
9. Right, let’s get back to that tally chart...
... and change it into a frequency table
10. Frequency table
Song length Number of songs
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
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
Tally chart
11. Well, that bit was easy!
Now let’s display the information in a pictogram
12. 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
13. Now we can use those symbols to make a pictogram
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
What else do
we need?
What else do
we need?
Number of songs
Songlength
= 2 songs
14. We can
show the
same
information
in a graph:
We can
show the
same
information
in a graph: Numberofsongs
Song length
6
4
2
8
Which
length of
song is the
most
common?
3 min
to
3 min 29
sec
3 min
to
3 min 29
sec
This is
called the
mode
This is
called the
mode
16. Grouping dataGrouping 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.
17. What have we learned?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)
• 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)