Hot Stuff – Lesson 4 – How hot is it?
Students recognise heat and measure its effect using a thermometer. They also examine and use different types of thermometers and read temperatures using a standard analogue or digital thermometer in °C (degrees Celsius).
Introduction: Review prior learning about transfer of heat and phonons and introduce the learning intentions using Lesson 4 of the Hot stuff PowerPoint.
Discussion: Review the use of measurement and units from prior science and mathematics, discuss the importance of measurement, and introduce the temperature unit, degrees Celsius (°C).
Demonstration: Show students how to use a digital and a spirit thermometer and demonstrate measuring the temperature of a container of water. (See Reading a thermometer video)
Activity – Ice cold and boiling hot: Working in groups, students measure and record the temperature of an ice/water mix, cold tap water and boiling water under teacher supervision. (See Types of thermometers worksheet, and Measuring temperature worksheet: How hot or cold is it?)
Activity – Cooling down (see above video): Students carry out a simple investigation to record the temperature of water, with added ice cubes, as it cools. They read and record the temperature once each minute for five minutes.
Discussion: Through questioning, review learning about the movement of atoms and molecules and develop the idea that temperature is a measure of how fast atoms and molecules move.
Review and introduce the next lesson: Review the main learning from the lesson and add to the class Word Wall. Inform students that in the next lesson they will learn about a range of ways in which heat can be produced.
Students will:
- learn how to measure temperature using a digital and analog thermometer
- know that degrees Celsius, written °C, is the unit used when measuring temperature
- explain that temperature is a measure of how fast atoms and molecules move.
- Gather as many different types of thermometers that you have access to show students the range available: e.g. Galileo thermometer, general laboratory thermometer, outdoor/room thermometer, BBQ digital thermometer, cooking thermometer, body thermometer and infrared body thermometer.
- Source internet photos of other thermometers.
- Obtain a good amount of ice cubes/crushed ice and plan the lesson to ensure it doesn’t melt too much before use (e.g. using an insulated container, or retrieve from a freezer when needed)
- 2 large beakers or jugs of a water/ice mix
- Access to boiling water – one station well away from students supervised by teacher, e.g. using a portable hotplate, or a kettle with freshly boiled water (re-boiled occasionally)
- One spirit or digital thermometer per group
- Cups (one or two per group, preferably transparent)
- Ice cubes (for each group)
Review prior learning, focusing on: heat is the energy of moving atoms and molecules which vibrate and transfer their vibrational energy to other places by tiny ‘bundles’ of vibrational energy called phonons. The hotter an object is, the more phonons there are and the faster the atoms and molecules vibrate.
Introduce the Lesson 4 learning intentions using the Hot Stuff PowerPoint.
Discuss the importance of measurement through questioning:
- What do we mean when we say we will measure something? Measurement uses an instrument of some sort, for example a ruler or bathroom scales, to find the size, amount, weight, or degree of something; it normally uses standard units such as metre; and it should be objective in that two or more measurements of the same thing should be the same.
- When we take a measurement, we need to record two things. Can anyone tell me what the two things are? A number – to tell how many units of something, and the units – for example, metres to measure length or kilograms to measure weight.
- Ask students why we might want to measure the temperature of something or someone? Weather forecasting, to see if a person has a fever, cooking, comfort in your house, science investigations.
How do we measure temperature: Is today hot or cold?
- How do we know? How we feel, but we could also measure the temperature.
- What is our body temperature? About 37 °C.
- What instrument do we use to measure temperature? A thermometer.
Then introduce degrees Celsius (°C) as the common temperature unit. Demonstrate how to use a spirit thermometer and a digital thermometer.
Demonstrate how to measure the temperature of a container of water.
The following shows how to read a simple analogue thermometer:
What are some advantages and disadvantages of using a glass spirit thermometer compared with a digital thermometer?
Show students a range of thermometers and explain they will have a chance to examine and answer questions about each and write about them on their Types of thermometers worksheets.
Ask students to read the temperature shown on the diagram of each thermometer on the: Measuring temperature worksheet: How hot or cold is it?
On the right you will find a demonstration video for this activity and the next activity. We recommend viewing this video before proceeding with the text description below and in the next section.
Working in groups, students will:
- Measure and record the temperature of a container of icy water (water/ice mix).
- Collect about half a cup of water from a cold-water tap, then measure and record its temperature.
Danger: Take the temperature of the water boiling in a pot on a hotplate (or a freshly boiled kettle). Ensure students are careful not to burn themselves. Only one person at a time (or alternatively ask students to read the temperature using a thermometer which is held in a clamp in the boiling pot.)
Highlight the important temperatures of the freezing point of water (0 °C) and the boiling point of water (100 °C).
See the above activity video
Working in groups, students carry out a simple activity to measure the temperature of an ice-water mixture every minute for five minutes.
Students prepare a table to record their results:
| Time (minutes) | Temperature (°C) |
| 0 (start) | |
| 1 | |
| 2 | |
| 3 | |
| 4 | |
| 5 |
Working in groups students:
- measure the starting temperature of tap water in a half-filled plastic cup.
- place three ice cubes into the plastic cup of water.
- gently stir the ice/water mix, set the timer for 1 minute, and take the temperature at the same time as starting the timer. Students should watch the thermometer’s temperature reading and record their observations.
- record the temperature of the ice/water mixture every minute for five minutes, stirring between each reading.
Finally, students could represent their data in graphical form as a dot plot. (You might do this on the whiteboard as a class if you have not previously introduced dot plots.)
Review what has been learnt through a class question and answer session with questions such as the following:
- What instrument did we use to measure temperature? A thermometer.
- What units do we use to measure temperature? Degrees Celsius or °C.
- What happened to the temperature of the water when ice was added? The temperature of the water dropped.
- What happened to the ice? It slowly melted.
- Why did we need to keep stirring the water-ice mixture? Mix it up to spread or distribute the heat energy.
- Where did the heat energy move to? From the warmer water to the ice.
- What is temperature? Lead students to the idea that temperature is a measure of how fast atoms and molecules move. Molecules which are gaining heat energy will begin to move faster and those losing heat energy will begin to move more slowly.
Review the main learning from the lesson and add to the class Word Wall.
Inform students that in the next lesson they will learn about a range of ways in which heat can be produced.
Temperature: is a measure of how hot or cold something is and is commonly measured in units of degrees Celsius, or °C. Heat energy moves from regions of higher temperature to regions of lower temperature as phonons spread out.
Thermometer: is an instrument used to measure temperature.
Analog thermometer: a thermometer that relies on a physical indicator such as the level of a liquid in a fine tube as it expands when it gets hotter and contracts when it cools.
Digital thermometer: has an electronic sensor that measures temperature and displays this as a number.
Temperature scales: there are three widely-used temperature scales: the Celsius (°C) scale is used in most countries and it is widely used in the sciences. The Kelvin (K) scale is also used in science, and is where absolute zero is the coldest temperature possible. At this temperature, all molecules stop moving. The Kelvin scale is obtained by simply shifting the Celsius scale so −273.15 °C coincides with absolute zero. The Fahrenheit (°F) temperature is used in the United States and a small number of other countries, and the conversion is a bit more complex.
Degree Celsius: is a temperature measurement unit based on water’s freezing point of 0 °C and boiling point of 100 °C. Sometimes also referred to as a ‘degree centigrade’.