## Thomaz et al. (1995)

This Portuguese paper discusses a teaching model focused on fostering conceptual change about heat and temperature. It evaluates its impact on the professional development of participating secondary school teachers with classes of students aged 14-15.

• Students have simplistic concepts of ‘heat’ such as ‘heat is sensation’ or ‘heat and cold are substances residing in objects’.
• Many students have a vague or incorrect understanding of the concept of temperature including ideas such as ‘temperature is a property of the substance from which a body is made’, 'temperature is something that can be transferred’, ‘temperature is a measure of a body's heat’ or ‘temperature is a function of heat’.
• Some students think that objects in contact for a long time with the same surroundings have different temperatures if their material is different.
• Students can believe that the state of ‘hotness’ or ‘coldness’ depends on the material from which the body is made.

### Teaching and Learning Implications

• Teach thermal equilibrium as the central concept from which all the other thermodynamical concepts to do with heat and temperature appear.
• Ask students to touch different objects in the room and describe their sensations (prompting discussion of what some students may think is 'temperature'). Then allow students to measure the temperature of these objects with a thermometer.
• A situation should be provided in which students can regularly measure the temperature of two objects brought into contact with one another until they reach equilibrium.
• Provide an experiment that allows students to visualise the effect of heating on the volume and pressure of a sample of air.
• Only after the above three steps should the term 'heat' be introduced as energy exchanged between equilibrating bodies.
• Discussion of thermal conductivity may be warranted to explain why different sensations do not mean different temperatures.

### Study Structure

#### Aims

The study set out to describe a teaching model aimed at promoting conceptual change concerning the concepts of heat and temperature.

#### Evidence collection

Data was collected via pre- and post-intervention diagnostic questionnaires which contained questions developed for this study. These questions are included in an appendix to the paper.

The responses to the questionnaires were analysed using simple quantitative techniques (a comparison of raw percentages) to show progress.

Teachers carrying out the course and tests also reported their observations about its outcomes.

#### Details of the sample

The study contained three phases, including two cycles of study:

• The first phase involved two secondary school teachers from the same school taking part in university-based sessions to discuss alternative conceptions to identify the problems.
• The first study cycle involved intervention on 92 students across 2 classes with students ages 14 – 15 years.
• The second study cycle involved intervention on 48 students from a single class with students ages 14 – 15 years.