2 Purposes of investigations
As well as being motivating and encouraging positive attitudes towards science, investigations are an important strategy in supporting your students’ learning. You might use practical investigations in your teaching for several purposes, including as a means to:
- developing students’ skills, e.g. devising a procedure, measuring, observing and data collection, presenting data, or critical evaluation
- supporting students’ scientific understanding of a concept, e.g. friction or chemical change
- developing students’ understanding of the scientific method, particularly fair testing.
The scientific method involves students in the following:
- Identifying a question
- Stating a hypothesis or prediction
- Identifying the variables
- Planning the experiment
- Carrying out the experiment
- Recording observations
- Interpreting results
- Drawing conclusions
- Presenting the findings.
As the teacher, you need to support your students in thinking and working scientifically. Resource 1 provides ways in which you can help your students. It is not necessary for your students to do all the steps every time you undertake an investigation in your classroom. It is possible to use the scientific method flexibly and focus investigations on one or two aspects at a time depending on your students’ experience and ability in doing investigations. So for example, you might focus your teaching on helping the students learn about how to present or interpret their results.
Pause for thought
Which purposes of investigation do you think are most appropriate for the students you teach?
The next case study looks at setting up an investigation.
Case Study 2: Investigating reversible and irreversible changes
Mr Sharma introduces reversible and irreversible changes to his Class VI students. Here he explains how he set up the students’ investigation.
I started by asking the students to make objects from pieces of paper by folding it. They made all sorts of objects, such as flowers, aeroplanes and boats. They enjoyed this very much. When they had finished, I told them that the school wanted the paper back and asked whether they could give the sheet of paper back again. The agreed that they could give it back. I told them that this was a reversible change, and wrote it on the blackboard.
Next, I demonstrated burning a piece of paper and asked them what they observed. I wrote their observations on the blackboard. I asked whether this was a reversible change and they said ‘No!’ I told them that this was an irreversible change, which I wrote on the blackboard.
I then told them that they were going to do a practical investigation into change. I had some materials that they could mix. These included mixing water with salt, flour, plaster of Paris and sand, as well as mixing vinegar with bicarbonate of soda or milk.
They worked in small groups to reduce the resources needed and recorded which substances they mixed and the changes they observed. I used some questions to help them observe the changes. For example, I asked what the original substances looked like compared with the mixture. I asked them if they had seen any bubbles or felt any warmth. I got them to look at texture as well. With each one they had to say whether they thought it was a reversible or irreversible change.
The students enjoyed this investigation very much and mixed lots of substances. Lots of the students could identify the reversible mixtures, but some – like plaster of Paris and water, and salt dissolved in water – they weren’t sure about. I kept these mixtures to look at next time.
Pause for thought
Practical investigations develop communication, groupwork and scientific skills such as observation, recording, handling materials and equipment, and working safely. Providing opportunities for students to talk whilst carrying out such investigations encourages deeper thinking and better understanding – see Resource 2, ‘Talk for learning’, for more information about talk in lessons. By getting students to present their findings you can also support the development of their presentation skills and build confidence in speaking to groups.