The day drawn in bars

Choose −3 for morning, 0 for afternoon, and 4 for night. Describe what changed using “colder” and “warmer.”

Em telas pequenas, deslize o gráfico na horizontal para ler os detalhes.

The length of the bar shows the distance to zero; the position shows whether the temperature is positive or negative.

Check out a comparison

Which is bigger: −5 °C or −2 °C? Which is closest to zero?

Check out the discovery

−2 °C is larger and closer to zero. −5 °C is five degrees below zero; −2 °C is two degrees lower.

A reference point

Imagine a thermometer. Zero is a reference mark: temperatures can be above or below it. We write +3 °C for three degrees above zero and −2 °C for two degrees below zero. The positive sign can be omitted: +3 and 3 represent the same number.

Explore the positions

In the figure, leave the variation at zero and move the starting point. Look for −2, 0, and 3. Negative numbers are to the left of zero; the positive ones, on the right.

Em telas pequenas, deslize o gráfico na horizontal para ler os detalhes.

First explore the positions. Then try moving one unit at a time.

Drawing game

Draw a thermometer with marks from −3 to 3. Color the zero mark and indicate −2 and 3. What temperature is closest to zero?

Check out the discovery

−2 is two units away from zero and 3 is three units away. Therefore, −2 is closer to zero even though it is the lowest temperature.

Connection to measurements

Temperature and length measure different quantities. A thermometer may read −2 °C, but the length of a pencil is not negative. The meaning of the number depends on what we are representing.

Continue with measurements to explore length and time.