Temperature and its Measurement — Evidence, Scales and Instruments (1 of 3) · Learner pages

Lesson 1 · Use measurement beyond touch

Explain why sensations alone cannot reliably compare temperatures.

Name or initials: ____________   Date: ____________

Temperature measures how hot or cold something is. Sensation depends partly on prior experience, so a thermometer is useful when we need a repeatable comparison.

1. Compare two reports. Use this supplied scenario rather than a hand-dipping experiment: one hand was in comfortably cool water and another in comfortably warm water. In the same middle water, the hand from cool water feels warm, while the hand from warm water feels cool.
2. Identify the common sample. The two reports concern the same middle water at the same time. The different sensations do not establish two different water temperatures. Prior experience can influence what feels warm or cool.
3. Use an instrument. The model thermometer gives 25 °C for the middle sample. A correctly used suitable instrument provides a measurement that can be recorded and compared. Do not touch unknown hot or cold objects to investigate their temperature.
4. Record a complete result. A useful record says which sample was measured, the temperature, its unit and the time or conditions when relevant. “25” alone does not identify the temperature scale.

Worked example: Two supplied reports describe the same classroom water: “cool after warm water” and “warm after cool water”. The instrument reading is 25 °C. The evidence supports a difference in sensation, not two simultaneous temperatures for the same well-mixed sample.

1. Two hands feel the same water differently after different prior conditions. What does this show?

   1. Sensation alone can be unreliable for comparing temperature · 2. The water must have two temperatures at the same place and time · 3. The thermometer must always be wrong

2. Which instrument measures temperature?

   1. Ruler · 2. Measuring jug · 3. Thermometer

3. Which is the most complete temperature record?

   1. Water A looks clear · 2. Water A: 25 °C at 10 am · 3. 25

Discuss: Write a claim-evidence explanation for the supplied scenario. Include one reason to use a thermometer and one piece of information missing from a bare reading of “25”.

Explain or demonstrate

Explain the two-hand supplied scenario using observation, conclusion and a complete instrument record.

Evidence to include:

• Different sensations acknowledged
• Same sample distinguished from sensation
• Number and unit recorded

Lesson 2 · Read temperature scales and symbols

Use Celsius, Fahrenheit and kelvin symbols correctly and perform a supplied Celsius-to-kelvin conversion.

Name or initials: ____________   Date: ____________

The same temperature can have different numbers on different scales. Always compare the scale as well as the number. The SI unit of temperature is kelvin, symbol K.

1. Name the scale. The model shows 37 °C, 98.6 °F and 310.15 K as three expressions of the same temperature. A different number does not automatically mean a hotter object when the units differ.
2. Write the symbols. Write a space between the number and unit: 20 °C, 68 °F or 293.15 K. The degree sign belongs with °C and °F; kelvin is written K. The unit name kelvin begins with a lower-case letter.
3. Apply a stated conversion. To convert a Celsius value to kelvin, add 273.15. For example, 20 + 273.15 = 293.15, so 20 °C = 293.15 K. The objects do not become hotter because the scale changes.
4. Keep reference values in context. 37 °C is a familiar approximate human-body reference, not a required value for every person at every time. This lesson uses it only to understand scales; a health judgement cannot be made from this comparison alone.

Worked example: A supplied room record is 25 °C. On the kelvin scale it is 25 + 273.15 = 298.15 K. The higher numeral describes the same room condition, not a new measurement after heating.

1. Which is the SI unit of temperature?

   1. gram (g) · 2. litre (L) · 3. kelvin (K)

2. Which symbol is written correctly?

   1. kG · 2. K · 3. °K

3. Using K = °C + 273.15, what is 20 °C in kelvin?

   1. 293.15 K · 2. 253.15 K · 3. 20.27315 K

Discuss: Correct these records with units and explain your corrections: “298.15 °K” and “37 is cooler than 98.6” when the original values were 37 °C and 98.6 °F.

Explain or demonstrate

Express 22 °C in kelvin using the supplied rule. Explain why the room did not heat up when you changed the numerical scale.

Evidence to include:

• 273.15 added correctly
• K written without a degree sign
• Same temperature explained

Lesson 3 · Choose a suitable thermometer

Check an instrument’s intended purpose, range and instructions before interpreting a measurement.

Name or initials: ____________   Date: ____________

Thermometers differ in purpose, design, range and reading method. A clinical thermometer is intended for body-temperature measurement; a laboratory thermometer serves other investigations. A digital display alone does not establish the intended use.

1. Read the instrument information. The diagram gives two illustrative devices with labelled purposes and ranges. Real devices differ, so consult their actual labels and instructions instead of assuming every clinical or laboratory thermometer has these exact endpoints.
2. Match purpose and required temperature. Model A is intended for clinical use from 35 °C to 42 °C; model B for laboratory use from −10 °C to 110 °C. A supplied 18 °C water sample is outside A’s range and inside B’s range, but safe use still depends on the manual and setup.
3. Keep uses separate. Do not use a laboratory glass instrument in a person’s mouth. For this course, read supplied digital displays rather than measuring classmates. Any real clinical measurement belongs with a responsible adult following the device instructions, including cleaning and contact method.
4. Recognise different designs. A contact digital thermometer uses a sensor in contact with the intended measurement site. An infrared design detects radiation without the same contact. Follow the particular device’s instructions; distance and position are not interchangeable across models.

Worked example: A supplied task asks for a reading of room-temperature water near 18 °C. The example clinical device A cannot cover that value. Example laboratory device B covers it and is intended for suitable laboratory work. Choosing B still requires the stated safe method; range alone is not permission to use any object in any way.

1. What should be checked first when choosing a thermometer?

   1. Only the number of buttons · 2. Its intended purpose, range and instructions · 3. Only its colour

2. Model A measures 35 °C to 42 °C. Can it measure an 18 °C sample within its stated range?

   1. No; 18 °C is below its lower limit · 2. Yes; all thermometers measure every temperature · 3. Yes; 18 has two digits

3. Which course activity is appropriate?

   1. Put a laboratory glass thermometer in a classmate’s mouth · 2. Test boiling water with a clinical thermometer · 3. Read supplied digital thermometer data

Discuss: Using two supplied device cards, match one classroom measurement to a suitable instrument and state two pieces of evidence for the choice. Do not measure another learner’s body temperature.

Explain or demonstrate

Model A is clinical, 35–42 °C. Model B is laboratory, −10–110 °C. For supplied 18 °C water, choose a candidate and explain why range alone is not the entire decision.

Evidence to include:

• Range comparison
• Intended purpose checked
• Actual instructions acknowledged

Final check · Set 1

Try one set after the lessons. Use the other set after reviewing any errors.

1. Why not test an unknown hot object by touch?

   Touch always gives an exact temperature / Touch changes every material into water / A suitable instrument and safe method avoid relying on a potentially harmful touch test

2. A report says only “the temperature is 25”. What essential information is missing?

   The number of letters in the report / The unit or temperature scale / The object’s favourite colour

3. Convert 0 °C to kelvin using the supplied rule.

   −273.15 K / 273.15 K / 0 K

4. Which record correctly includes the temperature scale?

   18 °C / 18 degrees with no scale / 18 g

5. Does a digital display prove a thermometer is suitable for every task?

   No; purpose, range and method still matter / Yes; digital means unlimited range / Yes; display colour sets the measurement range

6. How does an infrared design differ from a contact design in this lesson?

   It measures temperature by counting letters / It needs no correct positioning or instructions / It can measure without the same direct contact, following its own instructions

Final check · Set 2

Try one set after the lessons. Use the other set after reviewing any errors.

1. Which is a measurement rather than only a sensation?

   The display reads 24 °C / The water feels quite warm / The cup looks cheerful

2. A reliable comparison between two cups should include…

   Only which cup feels warmer to one hand / Only the cups’ shapes / Readings made with a suitable instrument using a consistent method

3. A supplied value is 25 °C. Its equivalent on the kelvin scale is…

   248.15 K / 273.40 K / 298.15 K

4. What does the familiar 37 °C body-temperature reference mean in this lesson?

   Any difference automatically identifies an illness / An approximate reference for comparing scales, not a diagnosis or a fixed value for everyone / Every healthy person must always measure exactly 37 °C

5. Model B is marked −10 °C to 110 °C for laboratory use. What can be concluded about 18 °C?

   Every clinical use is now permitted / It is inside the stated range; method and purpose still need checking / It is above the highest value

6. A real device has a different range from the diagram. Which information should be used?

   The real device’s verified label and instructions / Always the illustrative diagram / Whichever range gives the preferred answer