Here is one ordinary six-sided die. If we roll it lots and lots of times, do you think every number will come up about the same amount, or will one number win in the end?

Watch three things here. First, a single roll shows one face. Next, ten rolls can look lopsided — one number pops up more than its share over a short run. Last, a fair spinner has equal segments, so no colour is favoured even when a short run looks uneven.

Look for the equal-sized parts: on the die every face is the same, on the spinner every segment is the same.

Today we work through this together: we predict, then spin, then check. First the class predicts which colour a fair spinner will favour over twenty spins. Then a pupil spins twenty times and we tally each result on the board. After ten spins we pause and read the running tally, then finish to twenty and read it again.

Today we test three predictions, one harder than the last. For each one we predict first. Then we roll and tally. Then we judge whether the prediction held. Watch the board and agree or correct out loud.

• Is every die number about equal over twenty-four rolls?
• If one number races ahead in the first few rolls, does that mean the die is unfair?
• Do more rolls make the counts fairer? Compare ten rolls with thirty.