Here is a finished tally of our class's favourite school dinners, all the marks filled in. Look at it for a moment. How many children chose each dinner? And here is the real question: how did you count those gates of five so fast?

The frequency is just the total number of marks in a row. A gate of five is the crossed group of five marks: four upright strokes with one stroke laid across them. Watch as each tally turns into a frequency number. We count every full gate of five first, then add on the single marks left over.

A row of 6

One full gate of five, then one more on its own. Five and one is six. We write 6 in the frequency column.

A gate of five and three more

One full gate of five, then three single marks. Five and three is eight, so the frequency is 8.

A row of 12

Two full gates of five, then two single marks. Five, ten, and two more is twelve. The frequency is 12.

An empty row

No marks at all. Nobody chose this one, so the frequency is 0.

Today we work through a real class tally together: turn each row of marks into its frequency number. We will count every full gate of five aloud before we check it, and then read off which playground game won.

Now we work out the frequency for some rows described to us in words, then add them all up. First a row with no full gate yet, then a row with one gate and four more, then a row with two gates and three more, and finally the total of all three rows added together. We will say how we worked out each number before checking it.

What we learned

• Every tally turns into a frequency number when we count the marks, grouping in fives.
• A frequency table sets those numbers side by side so we can compare which answer is most common.
• Adding all the frequencies together gives the total number of answers collected.

Coming up