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?

A gate of five is four upright strokes with one laid across them; the frequency is just how many marks are in the row. Watch as we turn each tally row into a frequency number. Count the full gates of five first, then add on the single marks left over.

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 four single marks and 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.