Understand Temperature Scales
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What you will learn
- 1Read both Fahrenheit (°F) and Celsius (°C) scales on a thermometer
- 2Identify the displayed temperature on either scale
- 3Recall the key Fahrenheit benchmarks (32, 50, 68, 86, 98.6, 104, 212°F) and the matching Celsius benchmarks (0, 10, 20, 30, 37, 40, 100°C)
- 4Match everyday scenes to their correct temperature in °F and in °C
Mini Lesson
Temperature tells us how hot or cold something is. In the United States we usually measure temperature in degrees Fahrenheit (°F). In most other countries — and in science — temperature is measured in degrees Celsius (°C). A thermometer is the tool we use; many US thermometers show both scales side by side.
Two scales on one thermometer
- Fahrenheit (°F) — the US everyday scale. Water freezes at 32°F and boils at 212°F.
- Celsius (°C) — the metric and science scale. Water freezes at 0°C and boils at 100°C.
- A US wall thermometer often shows °F on one side and °C on the other side of the same column.
Reading a dual-scale thermometer
- Find the top of the colored liquid column.
- Read the number on the scale at that level — pick the °F side or the °C side.
- Higher number = hotter. Lower number = colder.
- Numbers below zero are written with a minus sign, for example -10°F or -5°C (very cold).
Key temperature benchmarks (°F first, °C second)
- 32°F / 0°C — water freezes, ice melts. Very cold — wear a heavy coat.
- 50°F / 10°C — cool fall or spring morning. Wear a jacket.
- 68°F / 20°C — comfortable room temperature. Just right indoors.
- 86°F / 30°C — warm summer day; a hot beach day can reach 95°F / 35°C. Wear light clothing, stay hydrated.
- 98.6°F / 37°C — normal human body temperature.
- 104°F / 40°C — very hot day, or a high fever. Tell a grown-up.
- 212°F / 100°C — water boils. Extremely dangerous — do not touch!
Matching °F and °C
- You do not need to do math at Grade 2 — just memorize the benchmark pairs above.
- Notice: when °C goes up by 10, °F goes up by 18.
- A handy fact: 32°F is the same as 0°C — the freezing point of water.
Words to know
Temperature
How hot or cold something is
e.g. Today's temperature was 68°F (20°C).
Thermometer
A tool used to measure temperature; US thermometers often show both °F and °C
e.g. The thermometer shows 86°F on one side and 30°C on the other.
Fahrenheit
The everyday US temperature scale, written °F
e.g. Water freezes at 32°F.
Celsius
The metric and science temperature scale, written °C
e.g. Water boils at 100°C.
Freezing
When water turns to ice, at 32°F / 0°C
e.g. At 32°F (0°C) the lake's surface is freezing.
Boiling
When water bubbles into steam, at 212°F / 100°C
e.g. Boiling water can burn you, so be careful.
Body temperature
The normal warmth inside a healthy body, about 98.6°F / 37°C
e.g. Body temperature stays close to 98.6°F (37°C).
Ask yourself: "Is the scene cold, cool, warm, or hot? Which °F (and °C) benchmark matches best?"
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