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Mathematics: relationships for creating · Lesson 01 / 08

Above and below zero

Tico’s square has an imaginary weather station. Its display reads −3 °C and then rises by 5 degrees. The minus sign tells a story: we are below a reference.

Learning paths8 min

Let's discover together

  1. 1

    On a number line, values increase to the right: −3, −2, −1, 0, 1, 2. Zero is a reference; 0 °C does not mean no temperature.

  2. 2

    Start at −3 and move five steps: −2, −1, 0, 1, 2. So −3 + 5 = 2. The final temperature is 2 °C; the change was 5 degrees.

  3. 3

    Now imagine 2 °C falling by 4 degrees: 1, 0, −1, −2. The result is −2 °C. Keep the sign: −2 and 2 occupy different positions.

  4. 4

    Write the unit with the result. In programming, position, change and unit also need meaning; a correct calculation can answer the wrong question.

✦
YOUR MISSION

Distinguish a position from a change; use a number line to interpret integers.

Now it's your turn

Discovery workshop

The display and the change

Trial 1: −3 °C + 5 degrees. Trial 2: 2 °C − 4 degrees. These are separate examples.
Build your answers and check when you are ready.
A moment to understand

Why is the result 2 different information from the change 5?

I need a hint

Mark the starting point first, then count the steps.

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Take it with you

Draw or describe a line from −5 to 5. Invent a starting position and two moves; record the results and a fictional unit.

At your own pace

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