Here is something we could find out about our own class today: What is everyone's favourite GAA county? How do we get to school each morning? How many pets do we have between us?

Which of these would be easy to count, and which would be tricky? Hands up if you have a question you would love to ask the whole class.

Look at these tallies of "favourite fruit" from a class. Each vote is one mark in that fruit's row. Notice that instead of five marks in a line, the fifth one is drawn straight across the first four, like a gate. That gate lets us count in fives.

Look at the three tallies below. The first shows five votes for apple, which is one full closed gate. The second reaches seven, which is one full gate and two more. And the last one is finished, so we read each row back as a total.

Today we run our own class survey on the board: we will agree one question with a clear set of answers, then keep a live tally as everyone calls their choice. One pupil is the recorder at the board, and the class agrees or corrects each mark as it goes in.

Now we set up and keep a tally for two class surveys on the board, the second a little trickier than the first. For each one we first agree a sensible set of answers, then we count vote by vote. The two surveys are:

• Favourite break-time game — we agree three answers, then tally each vote.
• Letters in your first name — we group the answers into bands (1–3, 4–6, 7 or more), then tally.