Negative numbers

For grown-ups: this lesson in words

Years 4 to 6 · Maths

Negative numbers: I can count through zero, read negative temperatures and put negative numbers in order.

1. This thermometer measures how warm or cold it is, in degrees Celsius.

   In the afternoon the liquid is at 3 °C.

   A frosty night comes. The liquid sinks below 0, to −2 °C.

   Numbers below zero are negative numbers. We say negative 2, or minus 2.

   Picture: A thermometer from -10 to 10 degrees Celsius, labelled every 5, with 4 small marks between the labels. It shows -2 degrees Celsius. It went from 3 degrees Celsius to -2 degrees Celsius.

2. A number line from −5 to 5. Zero is in the middle. Left of 0 are the negative numbers: −1, −2, −3, −4, −5.

   Start at 2 and count back: 1, 0.

   Keep going past zero: −1, −2.

   Counting back through zero takes us into the negative numbers.

   Picture: A number line from −5 to 5, labelled every 1. A dot at 2 labelled "start". The frog hops from 2 to 1, then to 0, then to −1, then to −2.

3. Your turn: Start at 1 and count back 3. Tap the number you land on.

   Picture: A number line from −5 to 5, labelled every 1. A dot at 1 labelled "start".

   Tap the right part of the picture.

   Answer

   The answer: -2

   1, 0, −1, −2. Three hops back from 1 lands on −2.

   Picture: A number line from −5 to 5, labelled every 1. A dot at 1 labelled "start". The frog hops from 1 to 0, then to −1, then to −2.

Words to know

negative number:

A number less than zero. It has a minus sign in front, like −3.

zero:

0, the number between the negative numbers and the positive numbers.

degrees Celsius:

The unit for temperature, written °C. Water freezes at 0 °C.