5 Developing students’ scientific understanding
Now read Case Study 3 and read Resource 2, ‘Assessing progress and performance’, especially the sections on assessment for learning and knowing where students are in their learning.
Case Study 3: Developing students’ understanding of the difference between heat and temperature
In this case study, Mr Mishra talks about the lesson he did after he had found out about the ideas his students held about heat and temperature, as described in Case Study 1.
The lesson involved students investigating changes in temperature when water at different temperatures is mixed in different volumes. I gave them some volumes to do, but said they could do others as well if they had time. I wrote the instructions on the chalkboard. The students had to complete a table of results. They recorded the volumes of the water and the starting temperature. They had to predict the resulting temperature and then record the actual temperature.
Once they had done this, I did a demonstration to explain what happens. I used a model to aid my explanation. I used a dye to represent heat. The intensity of the colour represented the temperature. I had several clear containers already prepared with different amounts of dye to represent water at different temperatures. I checked the students understood the model by asking them to tell me what order to put the containers in, going from coolest to hottest. Even the ‘cold’ beaker had some dye, although it was very pale. I then mixed different amounts of the different concentrations to show what happens when different volumes of water at different temperatures were mixed. Each time I asked the students for their predictions and gave them time to talk with their neighbour.
The students liked this and enjoyed making the predictions about what would happen to the colour. They seemed to find it easier to predict and didn’t make the same mistakes as they did before.
Once they had seen the demonstration, I asked them to discuss and explain the results from their practical investigation and predict what would happen in other situations I gave them. I could see that this activity had helped them to gain a better understanding of heat and temperature. It had changed their ideas about heat and temperature.
Mr Mishra’s model appeared to help his students understand heat and temperature. He made the abstract concept of temperature more concrete by replacing it with colour intensity. The students could see the resulting ‘temperature’. This helped them to gain a qualitative understanding, before going on to develop a quantitative understanding.
 Pause for thought
|
When using analogies and models, you must be alert to the limitations and the possibility of reinforcing alternative conceptions. The dye model used by Mr Mishra might reinforce the idea that heat is a substance that flows. It is also limited by being a static representation. Whereas a hot liquid will cool, this is not shown by the dye model. The best way to deal with these limitations is to ask the students why the model is not a perfect one and what it does show. Also note that Mr Mishra did not add the dye to the water in front of the students, as this would have reinforced the idea that heat is a substance.
Activity 3: Teaching about heat and temperature
You are now going to teach your students in order to develop their understanding of the difference between heat and temperature. You should read Resource 4 before you start your plan as this will help you decide what to do. You need to plan for the activity following these steps, but before you start, read the key resource ‘Planning lessons’, which summarises the key stages in planning and offers insight into the importance of planning. You need to plan for the activity following these steps:
- Identify what you want your students to learn from this activity and what alternative conceptions you will focus on.
- Decide on how you will challenge their alternative conceptions or present the new ideas. For example, you might measure the temperature of iced water, heat the water with a candle and ask where the heat has gone, even though the water is still cold.
- List the apparatus and materials you will need.
- Decide how you will organise the activity. It might be a demonstration or a class practical activity.
- Decide whether you want the students to work in pairs, groups or individually.
- Decide how you will support those who need more help with their learning.
- Plan your explanation. How will you explain the ideas that you want them to learn? Will your explanation use a model or an analogy? For example, you could use the dye model to show that even cold objects have heat energy.
- What will your students do with the new ideas to consolidate them? Will they discuss and apply them to new contexts? Or will they work on other examples? For example, you could give them some true/false questions.
Most of your students will have alternative conceptions, beliefs or theories of their own in many of the science topics you teach. Therefore, you need to become aware of the ideas your students already hold about the science you are teaching by providing opportunities for them to reveal and discuss their ideas. This will reveal the issues for you to address as you plan your lessons.
4 Helping students to change alternative conceptions