Numbers keep going below zero. Read the thermometer, ride the lift down to the basement, and find out which is colder.
Read where the red line stops.
0 is in the middle. Above it are positive numbers, below it negative ones.
Going up (warmer, or higher) adds.
Going down (colder, or lower) takes away.
The lower a number is, the smaller it is: −8 is less than −2.
Use something they know that goes below zero: a thermometer in winter, or a lift going down to a car park under the ground. Zero is the ground floor, and the floors underneath are −1, −2, −3.
−8 is further below zero. On a thermometer, −8°C is lower down and colder than −2°C, and on a number line it is further to the left. The bigger the number after the minus sign, the smaller the number.
Count steps on a vertical number line. Adding moves up, taking away moves down. From −3, going up 5 steps lands on 2; from 2, going down 5 steps lands on −3. Count each step, not the number you start on.
Children meet negative numbers in context, such as temperatures, at about 8 to 9, count through zero at about 9 to 10, and calculate across zero at about 10 to 11.