How do you read a thermometer?

Look at the top of the coloured liquid in the tube and read the number on the scale right next to it. That number is the temperature, normally given in degrees Celsius (°C).

What does a negative temperature mean?

A negative temperature is a reading below 0°C, written with a minus sign, such as −5°C. It means something is colder than freezing point, like the inside of a freezer.

Is −5°C colder or warmer than −1°C?

−5°C is colder. With negative numbers, the further a value is below zero, the colder it is, so −5°C is colder than −1°C.

Why is 0°C important on a thermometer?

0°C is the dividing line between positive and negative temperatures, and it is also the freezing point of water. Numbers above it are positive (warmer) and numbers below it are negative (colder).

What units do thermometers use?

In Singapore and most of the world, thermometers show temperature in degrees Celsius (°C). Some thermometers also display Fahrenheit (°F), but Celsius is the standard for school and weather.

Reading a Thermometer: Positive and Negative

Science Interactive lesson Free to play

Reading a thermometer means interpreting the scale to find the temperature, including values above zero (positive) and below zero (negative). On most thermometers a coloured liquid rises in a thin tube as it gets warmer and falls as it gets colder; the temperature is the number on the scale where the liquid stops, usually measured in degrees Celsius (°C).

This skill matters because temperature shapes daily life — checking the weather, knowing when food is frozen, taking a body temperature, or running a science experiment. In Singapore readings are almost always warm and positive, but freezers, fridges and colder countries produce numbers below 0°C, which need a minus sign and are called negative.

A learner grasps the key ideas: identify the parts of a thermometer and its scale; read where the liquid tops out; understand that numbers above 0 are positive and numbers below 0 are negative; and compare temperatures so that higher means warmer and lower means colder. Crucially, with negative numbers −5°C is colder than −1°C because it sits further below zero.

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Hot or cold?

🌡️ Temperature Detective Reading a Thermometer A thermometer tells us how hot or cold something is. 0° It's warm! 🔆 In this Spark you will learn to: Read the numbers up the scale 📈 Read positive temperatures (above 0°C) Read negative temperatures (below 0°C, with a minus sign) Decide which is warmer or colder ❄️🔥 Tap Next to begin, detective!
Meet the thermometer

The parts of a thermometer Tap each glowing ? to discover what it does. ? ? ? 👆 Tap a “?” Each part has a special job. Find all three! Found 0 of 3
Above zero (positive)

Reading above zero ☀️ The liquid rises as it gets warmer. Read the number where the red tops out. Read the red line What temperature is shown? Numbers above 0 are positive — just say the number, like “twenty degrees”. 15°C 20°C 25°C
Below zero (negative)

Going below zero ❄️ When it gets very cold, the liquid drops below 0. These numbers need a minus sign (–). We call them negative. 0 colder ⬅ ➡ warmer -10 -5 5 10 Brrr! What does this cold thermometer read? Below zero, count down from 0: −1, −2, −3… 5°C −5°C 0°C
Set it yourself

Your turn — set the temperature 🖐️ Drag the red liquid up and down the tube. Make it show the target! Target: 7°C Your reading: — Slide the liquid until your reading matches the target, then it locks in. ✅ Drag the liquid to begin…
Warmer or colder?

Which one wins? 🌡️ vs 🌡️ Remember: on the scale, higher = warmer, lower = colder. And −5 is colder than −1 (it is further below zero). Round 1 — Which is COLDER? 8°C or −2°C Round 2 — Which is WARMER? −5°C or −1°C
You did it!

🏅 Temperature Detective — Level Up! What you learned 🌡️ Read where the red liquid stops on the scale. ☀️ Above 0 → positive (just the number). ❄️ Below 0 → negative (add a minus sign, like −5°C). 📈 Higher = warmer, lower = colder. 🧊 For negatives, the bigger the number after the minus, the colder it is (−8 is colder than −2). Brilliant work — you can read any thermometer now! 🎉

Frequently asked questions

How do you read a thermometer?: Look at the top of the coloured liquid in the tube and read the number on the scale right next to it. That number is the temperature, normally given in degrees Celsius (°C).
What does a negative temperature mean?: A negative temperature is a reading below 0°C, written with a minus sign, such as −5°C. It means something is colder than freezing point, like the inside of a freezer.
Is −5°C colder or warmer than −1°C?: −5°C is colder. With negative numbers, the further a value is below zero, the colder it is, so −5°C is colder than −1°C.
Why is 0°C important on a thermometer?: 0°C is the dividing line between positive and negative temperatures, and it is also the freezing point of water. Numbers above it are positive (warmer) and numbers below it are negative (colder).
What units do thermometers use?: In Singapore and most of the world, thermometers show temperature in degrees Celsius (°C). Some thermometers also display Fahrenheit (°F), but Celsius is the standard for school and weather.

Reading a Thermometer: Positive and Negative

What this Spark covers

Frequently asked questions

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