Here are two winter mornings. In one town the thermometer reads −7 °C. In another town it reads −3 °C.

Hands up: which town is colder? And here is the tricky part — which number is actually the bigger number, −7 or −3?

The number line shows two markers at a time. Watch where each one sits: the number further to the left is always the smaller one. See if you can call the bigger number before it's confirmed.

Now we work through five pairs together on the board, deciding the bigger number in each one. For every pair we drag the two markers onto the line and read which one sits further right — that one is the bigger number. First predict, then place, then check as a class.

Now we work through five more together on the board, placing the bigger number of each pair: the bigger of −3 and −8, then the bigger of +1 and −5, then the bigger of −7 and −2, then the bigger of 0 and −9, and finally the bigger of −4 and −6. Predict where the answer lands before each marker goes down.