The Scientific Method
The scientific method is the sequence of activities which can lead to a discovery used in making almost all scientific enquiries. The scientific method is vital in finding out about our world and space. It is a requirement of every science curriculum that children and students are taught about it and that adults must know it, at least in outline, to be scientifically literate.
The steps of the scientific method
Briefly, the steps are:
- Looking by observing and finding patterns in the world you start on the path to discovery.
- Thinking of an idea to explain what has been seen (making a hypothesis).
- Predicting what you might find.
- Testing a prediction, this will usually be some form of experiment.
- Recording the results of experiments.
- Examine the data and Comparing the hypothesis and prediction with what was found out.
- Make a conclusion and explain what was found out.
Some lines of enquiry do not involve an experiment. These enquiries still involve other stages of the scientific method but the “trying to find out” part might be one of the following instead –
- Observing how a plant grows over time,
- Grouping a collection of specimens,
- Finding a pattern in a number of observations,
- Finding information in books or on the internet.
We’ll now take a look at the steps in more detail.
Observing is the scientific term you might like to use here. This can be observing a living thing, an object or an event that is happening such as feather falling to the ground. It can also be something you have seen in a book while researching a factual question on science, or in a TV programme on science.
In the poster it is the tripping up and spilling the contents of the curiosity box which provides a focus for the children to observe.
Thinking often takes the form of a question based on something noticed in step 1, the realisation that there may be a pattern. In the example on the sheet an interest is being shown in the way objects fall. “Do some things fall fast and some things fall slow?” At this stage the thought is not focused on testing by experiment.
When the children have come up with an idea to explain or describe the observation, it needs to be put it into a form that can be tested by experiment. It does not matter if the idea is “wrong” or “right”. In science, finding wrong answers can be just as important as finding the right ones
In the poster the first thought is restructured into a more specific idea which can be tested.
“I think heavy things fall faster than light things.”
The prediction is an educated guess based on the hypothesis. Again it is not important that the prediction is “wrong” or “right”. What is important is that the prediction is consistent with the hypothesis and follows on from simple reasoning. It is the prediction that can drive or help shape the investigation.
In the example on the poster the prediction is
“I predict this heavy rock will fall faster than this light rock.”
Note that the prediction is very specific to the two rocks but is based on the hypothesis that heavier things fall faster than light things.
The experiment is the test of the hypothesis and prediction.
There are three steps. In the poster, step three is shown but you should go through all the steps with the children prepare to reach step three.
A plan should be made considering what is actually to be done, what equipment is needed to do it, where it should be done, what might need to be done to ensure maximum safety, what can be done to keep errors to a minimum.
In the poster the plan is to have one person hold up the two rocks to the same height over a metal tray. One person is to time the fall of each rock, one person is to film the release of the rocks to check they are released at the same time. One person is to record the sound made by the rocks as they hit the metal tray. One person is to write down what happened.
2. Selecting or making your equipment
All the activities in my books involve everyday materials and equipment. Some pieces of equipment could be made for the children by you, such as the cutting the top off a plastic bottle and inverting it to make a funnel.
In the poster the children have selected a heavy and light rock, two stopwatches, a mobile phone set to record the sound, a video camera to film release of the stones, a clipboard, paper and pen.
3. Carrying out the planned experiment using the equipment
Once the equipment is collected and assembled it may help if the children practice by miming what is to be done before actually doing it. If measuring is involved they should practice making accurate measurements, such as with rulers.
This is the collecting scientific data often in the form of filling in tables but also in photographs and film.
The measurements or observations that are collected in the investigation is called the data. Observations may be recorded in tables, written accounts, labelled drawings or diagrams or photographs with captions.
In the poster the data is recorded on the stopwatches and transferred to the paper on the clipboard. It is also recorded on film and by a sound recording.
The data is often also called the evidence and this stage may also be called considering or evaluating the evidence. Sometimes people describe the data as the results of the investigation. Whatever term is used the data must be examined or analysed. In this activity the data is compared with the hypothesis and prediction. To guide your children and students in analysis you might like to use one of the following instructions, as appropriate, – arrange, order, divide, separate, compare and explain.
In the poster the film and sound recording are examined to see if the rocks were released at the same time (they were) and that the rocks hit the tray at different times making two sounds. (They did not. They made one sound indicating that they fell as fast as each other). The recordings of the stopwatches are now presented in a table and are shown to be identical (A further indication of the rocks falling as fast as each other). All this data is then compared with the hypothesis:
“Heavy things fall faster than light things.”
…and the prediction:
“The heavy rock will fall faster than the light rock.”
This examination of the data leads to the last step of the scientific method.
Make a Conclusion
The conclusion is a statement based on the examination of the data. The conclusion drawn in the poster is a generalization which sometimes occurs at the end of an investigation. More accurately the conclusion should be that the heavy rock and the light rock fell as fast as each other as this was the only fact that was discovered.
However, making a generalization allows further thought and the emergence of scepticism, a key feature in science enquiry to appear.
Scepticism is a disbelief in what has been presented. In the poster the conclusion is greeted by scepticism by one of the children who believes after considering a pine cone and a leaf that the conclusion is wrong. This can lead to another experiment and shows how the scientific method helps expand the discovery of knowledge.
You may like to ask your children how the conclusion could be modified to show a fact has been discovered and look for an answer about the heavy and light rocks falling as fast as each other.
You could also challenge them to compare the falling of a pine cone and leaf and to research to find out why they take different times to fall – the answer being that it’s due to air resistance.
Many people have difficulty with the idea of objects falling at the same rate so here is a simple explanation which I hope will help.
The idea that heavy things fall faster than light things was first put forward by Aristotle in Ancient Greece In his time everything was considered to be made of four elements – fire, water, earth and air. The elements in an object made it move in a certain way. It was believed that heavy objects contained a lot of earth and this drew them to back to the Earth quickly while lighter objects had less earth and were not drawn to the Earth as quickly. This idea prevailed until Galileo in the seventeenth century showed that weight does not affect the way things fall.
The reason for this is that gravity pulls on the objects and gravity is a force.
Newton’ s second law of motion describes a force as mass multiplied by acceleration.
F = m x a
All objects have mass and they also have inertia. This is a resistance to change what they are doing. If you push on a rock it does not move straight away you have to overcome its inertia to make it move. The amount of inertia is directly related to the amount of mass so the more massive the rock the more inertia it has and the more difficult it is to move.
You can think of inertia in a falling object to cancel out he effect its mass in the force equation so we have ..
F = a
..which in a falling object is the acceleration due to the force of gravity. This means that both heavy and light objects only have the force of gravity acting on them and this makes them fall as fast as each other.
How can I take part in science enquiries for the Science Enquiry Hub?
Begin by downloading the free scientific method posters which show the stages of the scientific method and use them to decorate an area that you will use as a laboratory to remind the students of the steps to take when making scientific enquiries.
Make scientific enquiries at home, in a science club or in class. If you’re not sure of where to start you could try using some of my books as starting points for ideas.
For 5 – 7 year olds
Ways into Science (Watts)
For 7 – 9 Year olds
For 9 – 11 year olds
[LINK] 100 Science lessons 2014 Curriculum (Scholastic)
Revise for Cambridge Primary Checkpoint Science Teachers Guide (Hodder Education)