KWL stands for ‘Know, Want to know, Learned’. You can use this strategy to help you keep track of what you already know, what you want to know and then, after the lesson, what you have learned that you didn’t know before.

This strategy is very useful when watching videos in class, but you can also use it at the beginning of a lesson, or the beginning of a whole module.

Suppose you are going to watch a video about earthquakes. You should never just watch the video without attempting to make notes. However, if you make too many notes you might miss something interesting or important. By using KWL, you can write down a few facts about asteroids before watching the video. You can also write down a few things that you want to learn from the video. While you are watching the video you can add new information in the ‘Learned’ column. It’s a great way to learn and a great way to increase your confidence about your own learning.

The example below shows how to lay out your page when doing a KWL exercise. It shows the ‘Know’ column filled in because that is the information that you already know. You should also fill in the ‘Want to know’ column before you watch the video. Remember that these are only examples. You might write some quite different things, and they would still be correct.

You would fill in the last column while you are watching the video.

I know that… / I want to know… / Learned
earthquakes happen in some places more than others. / which parts of the world get the most earthquakes?
the ground moves in an earthquake. / what makes the ground move?
scientists cannot predict earthquakes. / why can't they?
we only get small earthquakes in the UK. / why we don't get big earthquakes.
some earthquakes are bigger than others. / what is the biggest recorded earthquake?


KWL Grid

Know / Want to know / Learned


CAP stands for ‘consider all possibilities’. Sometimes, when you are given a question, there is only one answer: the right answer. However, sometimes questions have more than one answer that might be correct. For example, imagine that you have made an electrical circuit with a cell and a lamp, but it does not work. What are the possible reasons for this? It could be for lots of reasons such as:

the cell is flat the lamp is broken

the wires are not connected properly one of the wires is broken inside the insulation.

These are just some of the possible answers. You can probably think of some more of your own. Try out this idea by doing a CAP exercise on the following problems. Try to think of at least three possibilities for each problem.

1 Scientists cannot predict when an earthquake will happen.

2 A person is very thin.

3 A rope breaks when it is used to tow a car.

Now try to think of your own CAP type of question. Write it down, then write down three possible answers.

CAP problem:

Possible reasons:

1

2

3

4


PMI is a thinking skills exercise that stands for ‘plus, minus, interesting’. You are given a statement and you try to think of a plus point, a minus point and an interesting point (or interesting question) about that statement. For example:

‘The atmosphere should block out all ultraviolet radiation.’

Just read the statement and think of some possible answers. Here is an example of one PMI answer:

P: We would not get skin cancer from ultraviolet radiation.

M: We would never get a suntan.

I: Some insects see using ultraviolet – what would happen to them?

The great thing about PMI statements is that there isn’t just one correct answer. Have a go at the statements below. Try to make your answers as original as possible and don’t worry about what anybody else has written. Your answers are just as important and just as good!

1 A day on Earth should last for 30 hours.

2 No-one should be allowed to add polluting gases to the atmosphere.

3 People should not be allowed to live in earthquake zones.

4 Anything that is not completely safe should be banned.

5 You should only have to go to school until you are 10 years old.

PMI statement

Plus

Minus

Interesting

The scientific method is a way of testing ideas about things. The flowchart shows how this often works.

For the scientific method to work, the question must be a question that can be tested scientifically. For example, you could ask 'Are snowflakes beautiful?'. This is not a scientific question. You could ask people what they think, but then you would have found out how many people think that snowflakes are beautiful, which is not quite the same question!

In many cases, scientific questions are tested by carrying out experiments in a laboratory. However there are many scientific questions that cannot be answered in this way. For example:

Which animals and plants live in this habitat? You can’t do an experiment but you could carry out surveys in the habitat to find out.

Do people find people with a sun tan more attractive? You can’t do an experiment but you could do a survey to collect your evidence.


What is the inside of the Earth made of?

Scientists do some experiments with rocks, but it is not possible to drill a deep enough hole to get samples of rocks from the middle of the Earth. Scientists have to use many different forms of evidence to try to work out what the Earth is made of.

Will the Sun always stay the same?

Scientists cannot carry out experiments on the Sun, but they can gather information about our Sun using telescopes and space probes, and also look at millions of other stars. They use this information to work out theories about how and why stars change with time.

Peer review

When you carry out investigations at school, you know that your teacher already knows the answer to the question. However scientists working in Universities or other research departments do not know the 'answer' to the question they are posing. Their work is checked by the process of peer review.

When a scientist has finished an experiment and drawn a conclusion, she or he writes a paper which describes the experiment in detail, and gives the results and conclusions. This is sent to a scientific journal. The editors of the journal send the paper to other scientists in the field for them to review (check). Sometimes the first scientist is asked to check their results, or amend their conclusions if the reviewers think they may have made a mistake. This process is anonymous (the scientist's name is taken off the paper sent out for review, and this scientist does not know who the reviewers are). When the reviewers are satisfied that the paper is describing a good quality experiment and conclusion, the paper is published in a journal. (There is more information on peer review on Skills Sheet 5.)

Replication

The checking process continues after a paper is published. If the conclusion is an important new discovery, or contradicts earlier ideas, other scientists around the world may try to replicate (reproduce) the same experiment, or try slightly different experiments to answer the same question. Sometimes this process shows that the authors of the original paper made a mistake.

1 Why is peer review necessary?

2 Why do you think anonymous peer review is a good idea? Give as many reasons as you can.

3 Why do scientists publish their results? (There is more than one reason).

4 Why is it important that other scientists try to replicate experimental results?


Newspaper reports or news broadcasts often include claims for new scientific discoveries or new medical treatments.

Drinking tea prevents heart attacks!

Often, these claims are exaggerated or sometimes even wrong. Here are some questions that you can ask to help you to evaluate claims like this.

Are the results published in a scientific journal? Has the study been peer-reviewed?

Scientific papers are peer-reviewed before they are published in scientific journals. This means that other scientists working in the same area have checked the method and results. A news report taken from a paper in a scientific journal is more likely to be correct than a report based on talking to a scientist before his or her work has been peer reviewed.

How was the investigation carried out? Were there controls? Was the test fair? What was the sample size?

A trial to test whether changing your diet or taking a new medicine has health benefits is quite difficult and costly to carry out. A good trial would involve:

·  a lot of people, as people may respond to diet or medicines in different ways

·  a control group, consisting of people with the same medical problem (for a new medicine), or with similar diets, health and lifestyles (for a new diet). The control group would not get the new medicine or the new diet.

·  blind or double blind trials, if possible. In a blind trial, the subjects do not know whether or not they are getting the treatment. So, for a new medicine, the control group may be given sugar pills instead of the medicine. This is because sometimes just the belief that you are being treated can make you feel better. In a double-blind trial, some of the experimenters (or the patients' doctors) do not know which patients are getting the new treatment either. This is to make sure that any judgments they make about the patients' health is not biased by whether or not they expect the new medicine to be better.

How big was the effect?

A new diet that reduced the chance of a heart attack by 1 in 1 million people would not be worth bothering with. The number of heart attacks in the population could vary naturally by more than that amount. The results need to be 'statistically' significant, which means that the new medicine or new diet must make more difference than can be explained by natural variation.

Could the experimenters have been biased?

Who funded the study? For the headline above, you might be a bit suspicious if the study was paid for by a tea company. This does not necessarily mean that the study is biased, but it might be. For example, any bad effects of the new medicine or diet may have been ignored, or made to sound unimportant.

Could the reporters have been biased?

Information about the pollution caused by a power station might be reported very differently by a journalist working on an environmental magazine and one working on a magazine for the power industry.


Scientists argue about many things, such as the meaning of a piece of scientific evidence, how a particular organism should be classified, or the best way of explaining observations. This kind of argument does not (usually) involve shouting or insulting your opponent!

A good argument contains the following features:

·  a statement of what you believe

·  the evidence you are using to support what you believe

·  a counterargument (objections to what you believe, with evidence)

·  your response to the counterargument, saying why you think the counterargument is wrong

For example, you might argue that the Earth is a sphere, not a flat disc.

The Earth is spherical.

I think this because:

·  ships can sail right around the Earth
without reaching an edge

·  engineers put satellites into orbit using this idea,
and it works

·  photos of the Earth taken from space
show that it is spherical.

Some people say that the Earth must be flat,
as anyone on the 'bottom' of a spherical Earth would just fall off.

However these people don't understand gravity.
Gravity pulls all things together, so everyone on the Earth
is pulled towards the centre of the spherical Earth.

You don't normally need to use headings such as 'evidence' or 'counterargument', but you can make these sections clear by using the right sort of words.

Part of argument / Indicator words
your evidence / I think this because, as, since
a counterargument / Some people say, some people think, you could say that
response to the counterargument / however, but


Units are important. It is no use telling someone that a reaction happens in 15. Do you mean 15 seconds, 15 minutes or 15 hours?

Whenever you measure something in science, you need to know what the units of measurement are, and write the units down when you write the number. People in different countries used to use different units for measuring things. Scientists in different countries often share their results, and using different units could get confusing. Scientists have agreed that they will all use the same units when they make their measurements. The units they use are called SI units.

Table 1 shows the SI units that you will use in this course. Some units are combinations of other units.

Table 1 Some SI units

Quantity / Unit / Symbol
length / metre / m
area / square metres / m2
volume / cubic metres / m3
mass / kilogram / kg
force / newton / N
momentum / kilogram metres per second / kg m/s
pressure / pascal / Pa (1 Pa = 1 N/m2)
energy / joule / J
power / watts / W
current / amperes (amps) / A
charge / coulomb / C
potential difference / volts / V
resistance / ohm / W
temperature* / degrees Celsius* / ° C
time / second / s
velocity / metres/second / m/s
Acceleration / metres/second/second / m/s2
frequency / hertz / Hz
power (of a lens) / dioptre / D
concentration / grams per centimetre cubed+ / g/cm3
amount of substance / moles / mol

*degrees C is not the SI unit: if you study unit P3 you will learn about the Kelvin scale for temperature
+a convenient measure of concentration derived from the SI unit