Good Science Victorian Curriculum Year 7

CHAPTER 1: SCIENCE SKILLS
3
The independent variable is the one thing you want to change in
an investigation. If you change more than one thing, the investigation
probably won’t be a fair test.
Let’s say you decide to put three plants in three different amounts
of sunlight to see which plant grows the most. You would make sure
the plants were the same size, health and species, and only change
the amount of sunlight the plant is getting – this is the independent
variable. The dependent variable would be your measurement of
the plants’ growth (which could be their weight or their size) and the
controlled variables are all the other factors.
What are the three types of scientific variable?
A hypothesis is a prediction of the outcome
A hypothesis is a prediction made to test something. A good hypothesis
involves some reading and research so that scientists can make an
informed decision about what they think will happen, before testing it in
an investigation. A hypothesis can be supported (found to be correct) or
rejected (found to be incorrect).
You use the independent and dependent variables when writing
a hypothesis, so the first step is always to identify these. The general rule
to use when writing a hypothesis is:
independent
variable
If I do this , then this will happen.
dependent
variable
Even though this rule has the word ‘I’ in it, that’s not how you write the
hypothesis! You should always write it formally and in the third person
(don’t use I, we, you etc.).
What is a hypothesis?
Figure 1.9 These scientists
are doing fieldwork to test
water samples.
ELEMENTS OF AN
INVESTIGATION
Think again about the
investigation that involves
plants in different amounts of
sunlight to see which plant grows
the most. The elements of this
investigation are:
• hypothesis: If a plant is placed
in direct sunlight, then it will
grow more than a plant in
indirect or no light.
• independent variable: amount
of direct sunlight (one plant is
put in a dark cupboard, one is
put outside in direct sunlight
and one is put near a window)
• dependent variable: growth
of the plant, in millimetres
• controlled variables: species
of plant, starting size of plant,
health of plant, amount of
water given to plant.
TYPES OF
INVESTIGATIONS
Scientists do many different
types of investigations,
depending on their area of
science and the information
they need to gather.
Fieldwork happens when
information and data are
collected outside of the
laboratory or usual setting.
Environmental scientists often
do fieldwork, such as collecting
water samples from streams
to study the water quality or
counting the numbers of species
of plants and animals in an area.
Experiments are usually
carried out to test a hypothesis.
Experiments in science include
(among other things) those
undertaken in chemistry, physics,
earth science, and with living
things in biology.
Research informs a hypothesis
before it is created. Scientists
often share their research
so they can build scientific
understanding and discoveries
over time.
11