A possible approach to teaching investigation

Improving Science Education 5-14
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An Investigative Approach to Science

A possible approach to teaching investigation
Step 1 - Brainstorming/getting ideas	Step 2 - Choosing the variables
Step 3 - Asking a question	Step 4 - Planning the experiment
Step 5 - Carrying out the experiment	Step 6 - Recording & Presenting (1)
Step 7 - Recording & Presenting (2)	Step 8 - Recording & Presenting (3)
Step 9 - Interpreting & Evaluating (1)	Step 10 - Interpreting & Evaluating (2)
Step 11 - Reporting back

Step 1 - Brainstorming or getting ideas

Planning [1] What could we investigate?


What could we measure or observe?

The poster is made available to the children. This may be put up on the wall as a poster. An A4 copy may be made available or copies given to group leaders or to all of the children. The teacher then initiates a class discussion on the investigation topic.

Note - The following example refers to the unrevised 5-14 Guidelines :-

Planning [1] What could we investigate?
light	temperature	amount of medium
acid rain	seed type	closeness of seeds
What could we measure or observe?
light	temperature	amount of water

e.g. the investigation may reflect the key feature - Understanding Living Things and the Processes of Life - at the P4 to P6 stage factors which affect germination and growth (National Guidelines Pages 16-17).The teacher may begin by reminding the children about what germination means, then pose the question What affects germination? The purpose of the investigation is to discover if and how a particular factor affects germination in a particular plant, e.g. cress.

The children are asked to suggest any factor which might affect the germination of cress.

An example of an investigation from the Revised Guidelines may reflect the Attainment Outcome - Living Things and the Processes of Life - at the S1 stage (Level E) - Attainment Target - identify the raw materials, conditions and products of photosynthesis. The teacher may begin by reminding the children about what photosynthesis means, then pose the question - What affects the growth of the plant and its ability to photosynthesise? The purpose of the investigation is to discover if and how a particular factor affects growth in a particular plant, e.g. peas.

The children are asked to suggest any factor which might affect growth of the peas. As each factor is suggested it is added to the list, it may be helpful for the children to write these on Post-It pads and stick them to the poster; or they may draw a picture to illustrate these; or pictures may be supplied.

Step 2 - Choosing the variables

Planning [2]
I am going to find out what happens to ...
... when I change ...
I am going to keep these the same (constant) to make it fair ...

Once again the poster is made available to the children. This may be put up on the wall as a poster. An A4 copy may be made available or copies given to group leaders or to all the children.

The group are asked to select one of the variables which they will change
(independent variable), one they will measure (dependent variable). All the other variables must be kept the same if there is to be a fair test.

Fair Testing

The concept of a fair test is crucially important in planning an investigation. The children should be taught to control the other variables other than the dependent and independent variables in a conscious way. Often the more obvious a variable is the more likely it is to be controlled, but the children should be trained to consider their set up and decide on the variables to be controlled.

It is only by carrying out a fair test that you can be sure that it is what you have changed (independent variable) that is affecting what you measured (dependent variable).
It is easier to recognise that a test is fair than it is to plan and carry out a fair test.
You will need to encourage the children to make sure that all relevant aspects have been controlled (kept the same).
Most children need only say that they intend to keep certain things the same, but the most able children should be encouraged to discuss what value each control variable should have.

Note: the words independent variable and dependent variable need NOT be taught at this stage!

Step 3 - Asking a question

Planning [3]
Making a prediction/hypothesis
When we increase/decrease	temperature
... we think that the	number of seeds germinating
will increase / decrease / stay the same

At this stage the children are being asked to select the variable which they want to investigate. They choose one of the things which they have said they could change
and one of the things which they said they could measure. The question posed is: If I change this (the chosen variable), what will happen to that (the chosen measurement)? The chosen variable is known as the independent variable and the chosen measurement is known as the dependent variable but this need not be taught at this stage.

Step 4 - Planning the experiment

Planning [4]
Designing the experiment
Listing what you need	Describe how you will use them. Make a diagram if you want.
30 cress seeds cotton wool 3 dishes cling film thermometer water
1. Put a layer of about 2 cm depth of cotton wool in each dish. 2. Add 5 cm³ water to each. 3. Lay 10 cress seeds on top of each piece of cotton wool. 4. Cover the dish with cling film. Leave dish A at 10°C, dish B at 20°C and dish C at 30°C. 5. Leave each for 3 days, then count how many seeds have sprouted in each dish.

The children now plan the experimental procedure. It is very important to stress that only one of the variables can be changed during the experiment. As a result the variable being measured will, presumably, change. All other variables must be kept constant, that is they do not change. This is to ensure a fair test.

A fair test is one in which only the independent variable is seen to cause a change in the dependent variable. If for example two things change, say temperature and humidity, you cannot be sure which of these causes the change in the dependent variable; it may be temperature or it may be humidity or it may be a combination of both.

Step 5 - Carrying out the experiment

Before they carry out their experiment it is important that the teacher makes sure
that the procedure to be followed is safe. For this reason it is important to include a TEACHER CHECKPOINT before the pupils is allowed to continue with the practical and to ensure that suitable safety precautions are used.

The children collect evidence by carrying out the experiment and carefully noting the changes occurring in the dependent variable. They may also measure the variables they are keeping constant to ensure that they are kept constant throughout their experimental procedure.

Step 6 - Recording & Presenting (1)

What we changed	What we measured
temperature (°C)	no. of seeds germinating
10	5
20	7
30	9

The children are encouraged to record the results from their investigation by producing a table of results. The table includes the independent variable (what they were changing) and the dependent variable (what they were measuring).

The production of the table of results will assist the children in constructing a bar chart or graph of their results.

An average may need to be taken to get more accurate results.

Graphs and charts are powerful tools because they enable children to see the result of what they changed (the independent variable) affecting what they measured (the dependent variable). This gives a picture of the information they have collected and helps them to identify patterns and trends in the information. It also helps the children to develop understanding by relating pattern and trends to their scientific knowledge.

The type of graph which is appropriate depends on the type of variable which is used for the key variables i.e. what they change (independent variable) and what they measure (dependent variable). The table below shows the type of graphs which should be drawn for different types of variables.

Step 7 - Recording & Presenting (2)

What type of graph should be used?

What is ...

Type of table

Type of graph

... changed?
(independent variable) e.g.

... measured?
(dependent variable) e.g.

WORDS
type of cloth

WORDS
amount of wear

Type of cloth	amount of wear
cotton	slight change
nylon	no change
wool	lots of wear
linen	little change

no graph

WORDS
type of cloth

NUMBERS
size of stain (cm²)

Type of cloth	size of stain (cm²)
cotton	4
nylon	3
wool	5
linen	1

NUMBERS
length of elastic band (cm)

WORDS
pitch of note

length of elastic band (cm)	pitch of note
2	very high
4	high
6	medium
8	fairly low
10	low

no graph

NUMBERS
concentration of acid (%)

NUMBERS
no. of bubbles

concentration of acid (%)	no. of bubbles
5	4
10	10
15	13
20	18
25	20
30	24

Step 8 - Recording & Presenting (3)

Looking for a pattern in the results

What we measured		By careful examination of the bar chart or graph the children should be able to identify any trend or any pattern which appears in their results. In this case there is an increase in the number of seeds germinating with increasing temperature.
number of seeds germinating
	temperature (°C)

Step 9 - Interpreting & Evaluating (1)

Finding a pattern in the results

When we increased	temperature (°C)	The children are now asked to make sense of their results. At this stage the children are also asked to suggest any possible improvements to their experiment. The purpose of this activity is to allow them to evaluate the validity of their results.
There was ...	number of seeds germinating
an increase in the
~~a decrease in the~~
~~no change in the~~

Step 10 - Interpreting & Evaluating (2)

Drawing a valid conclusion

Was the investigation a fair test?	Yes	No	If they are satisfied that the experiment represented a fair test, they may now draw a conclusion from their investigation. If the experiment was not a fair test, no conclusion may be reached.
The conclusion from our investigation is ...
The number of seeds germinating is controlled by temperature. When you increase the temperature the number of cress seeds germinating increases.

Step 11 - Reporting back

After the practical part of the investigation is over, a reporting back session is vital. The importance of this stage is frequently under estimated and on occasion bypassed altogether (although admittedly often because of pressure of time). The reporting back session needs careful handling if the learning outcomes are to be fully achieved. It is at this point that the concepts of evidence take on their full impact because the pupils have to use their own evidence to justify the conclusions at which they have arrived.

The reporting stage can be followed by a consolidation stage where the pupils are encouraged to use the information they have gained to further advance their knowledge and understanding. This kind of reflective discussion, where the group outcomes are shared, can be very useful.