Last reviewed: 7 November 2026
Updated November 2026. These Grade 7 temperature notes explain how to describe and compare temperature, the units degrees Celsius (°C) and kelvin (K), and how to convert between them. To change °C to K, add 273. To change K to °C, subtract 273. So 25 °C = 298 K and 300 K = 27 °C. The kelvin scale starts at absolute zero, so it has no negative values.
The examples and questions are original practice for Kenyan junior school learners, not an official paper. For the other Grade 7 maths topics, see our Grade 7 mathematics revision guide and the Grade 7 notes hub.
On this page
What the Grade 7 Curriculum Covers
Temperature is a sub-strand under Measurements in the Kenya Institute of Curriculum Development’s Grade 7 Mathematics design. Learners describe temperature as warm, hot or cold, compare temperatures, identify degrees Celsius and kelvin as units, convert between them, and work out temperatures in real-life situations. The design is listed on the KICD Grade Seven curriculum designs page.
Describing and Comparing Temperature
Temperature tells us how hot or cold something is. Words like cold, warm and hot describe it; comparing words like hotter, warmer, colder and “same as” compare two temperatures. A cup of tea at 70 °C is hotter than a glass of water at 20 °C. A morning in Nyahururu is often colder than a morning in Mombasa. Numbers make comparisons exact: 18 °C is 6 degrees colder than 24 °C.
Units: Degrees Celsius and Kelvin
- Degrees Celsius (°C) is used in daily life, weather reports and clinical thermometers. Pure water freezes at about 0 °C and boils at about 100 °C at sea level.
- Kelvin (K) is the SI base unit of temperature, as described by the International Bureau of Weights and Measures (BIPM) page on the kelvin. It starts at absolute zero (0 K), the lowest possible temperature.
Note: kelvin is written without the degree sign: 300 K, not 300 °K.
A change of 1 °C is exactly the same size as a change of 1 K, so the scales differ only in their starting point. The exact relationship is K = °C + 273.15, as explained in NIST’s introduction to the kelvin. In Grade 7 work, 273 is normally used. Use whichever value your question gives.
Converting Between °C and K
| Convert | Rule | Example |
|---|---|---|
| °C to K | add 273 | 25 °C = 25 + 273 = 298 K |
| K to °C | subtract 273 | 300 K = 300 − 273 = 27 °C |
| Negative °C to K | add 273 | −10 °C = −10 + 273 = 263 K |
Worked example: boiling and freezing
Water freezes at 0 °C = 273 K and boils at 100 °C = 373 K. The difference is 100 °C, which is also 100 K.
Working Out Temperature Changes
Worked example one
In this made-up example, the temperature at 6 a.m. was 12 °C and at 2 p.m. it was 27 °C. Rise = 27 − 12 = 15 °C (also 15 K).
Worked example two: below zero
Meat in a freezer is at −18 °C. It is taken out and warms to 5 °C. Rise = 5 − (−18) = 23 °C.
Worked example three: average temperature
The midday temperatures for five days were 24, 26, 23, 25 and 27 °C. Average = (24 + 26 + 23 + 25 + 27) ÷ 5 = 125 ÷ 5 = 25 °C. In kelvin: 298 K.
Reading a Thermometer
Hold a thermometer at eye level and read where the liquid or display ends. Count the value of each small division first: if 10 °C is split into 5 divisions, each division is 2 °C. A clinical thermometer has a short range around normal body temperature, while a laboratory thermometer covers a wider range, such as −10 °C to 110 °C.
Original Practice Questions With Worked Answers
- Convert 37 °C to kelvin. 37 + 273 = 310 K.
- Convert 250 K to °C. 250 − 273 = −23 °C.
- Which is hotter, 320 K or 45 °C? 320 K = 47 °C, so 320 K is hotter.
- The temperature falls from 21 °C to −4 °C. Find the fall. 21 − (−4) = 25 °C.
- Can a temperature in kelvin be negative? No. 0 K is absolute zero, the lowest possible temperature.
Cover the answers and attempt each question first. For timed practice, use the Grade 7 revision papers or the Grade 7 CBC Challenge. These notes are free; full revision access is available with the KSh 20 Day Pass or the KSh 500 Monthly Pass.
Frequently Asked Questions
How do you convert Celsius to Kelvin?
Add 273 to the Celsius temperature (273.15 for exact work). For example, 20 °C = 293 K.
How do you convert Kelvin to Celsius?
Subtract 273. For example, 310 K = 37 °C.
Why does the kelvin scale have no negative numbers?
It starts at absolute zero, the lowest possible temperature, so nothing can be colder than 0 K.
Is a change of 1 °C the same as a change of 1 K?
Yes. The two scales have the same size of degree; only their zero points differ.