Recording Temperature Cold Hot Lesson

Learning experiences covered

• Number and counting.
• Quantity.
• Collecting data and drawing tables of data.
• Making comparisons.
• How to decide hot and cold.

Key Questions

1. How hot is hot and how cold is cold?
2. Why do you feel hot or cold?
3. Can you say exactly how hot or cold it is?
4. What are the units for temperature?
5. What does the word boiling describe?
6. At which temperature does water turn solid?
7. What is ice?
8. What wrong with saying it’s boiling (or freezing) to describe hot and cold?
9. If you see the temperature for tomorrow’s weather, can you say how it will feel?

You will need:

• Some hot and cold places to compare your body heat with the room.
• A logger and its software
• A computer.
• A projector for an (interactive) whiteboard.

Suggested method

Choose an activity that produces a real temperature difference in situations familiar to students. In this way there will be belief that the logger shows what they know but in different way.

1. Connect the logger to the PC and whiteboard, Set the software to show numbers as a set of blocks or bar chart. 2. Place the temperature sensor in your hand. 3. Talk about the level of the bar. Do a bit of counting, What does the bar mean? What are the numbers for?. Why did the temperature go up? Why did it stop going up? 4. Ask the class to suggest a cold place for a comparison (Maybe put some cold water nearby!) 5. Take the temperature of the cold place. 6. Talk about hot and cold. Use number lines to count differences. 7. Measure other places. Get the class to decide when it is hotter and when it is colder. Use the logger to see who can make the best guess.

Examples where we have to decide if it is hot or cold:

• Controlling the heating.
• Choosing clothes for a holiday.
• Eating or drinking.

There may be confusion between cold and feeling cold. All the objects in the room will normally be the same temperature as they will have reached a balance with the room temperature. However metal objects will feel colder, but they do not have different temperatures. Ask the students to go touch things to say if they are colder or hotter and be sure that they are different temperatures and they do not not just feel different! How hot it feels is subjective. A group of people in the same room, experience the same temperature. Why then do some people feel they have to open windows or ask if it is hot?

Use the logger as a standalone device The Vu logger is used as a standalone device for this activity. Use the Snapshot mode of the logger to record the data for each of the areas tested. You can show the data on the loggers screen using the review mode. Or you can connect the logger to a PC and use Remote, retrieve to download the data to the EasySense software. Use Meters mode to select and deselect which sensors will be active for the investigation. Instead of connecting the logger to the PC, the data can be copied from the screen onto a sheet

Teacher’s notes

This is an activity about measuring difference and giving a value to quantity. When is it hot and when is it cold? How do you decide when it is hot or when it is cold? We use the equipment sensor to give a value to statements like “it’s hot” or “it’s much colder”. Extremes of hot and cold are easy to deal with. It is obvious when a radiator is hot or the inside of a fridge is cold, but what about in the corner of the class where it is a little bit less hot or a little bit colder? Heat is a difficult topic. Heat is the energy but hot / cold is the sensation of the transfer of heat energy. If heat is moving in to us we feel hot, if it is moving out of us we feel cold. We are better is detecting relative change than detecting hot and cold.This is why draughty rooms or windy days feel colder. We need a thermometer to give a value for heat and allow comparisons. These are all ideas you can explore with a well-structured lesson. When finished the students should understand that hot is where there is “more temperature” and cold is where there is “less temperature”

These can then be explored:

• Why does it feel warmer on a sunny day?
• Why does it feel hot when you come into a room from a cold corridor and then it stops feeling warm?
• Why does wearing slippers make you feel warm?

We build on the idea of using number to define similarity, or difference, we also use the activity to introduce the logger as a normal piece of equipment. You may be surprised at how small changes in temperature make us feel hot or cold!

Word use Heat, hot, cold, boiling, freezing and temperature are used interchangeably in everyday speech. So it is often easy to forget that they have specific meanings. Use them consistently to avoid creating confusion. Take the time to correct wrong usage.

• Substitute the words into a simple sentence and see if they still make sense, for example “Is the radiator hot” sounds better than “Is the radiator heat”.
• Freezing is when a liquid turns to a solid and boiling is when a liquid turns to a gas. Very cold, or very hot are better phrases!