Observing and Hypothesizing Even though biologists and other scientists study many different types
of things, they all use the same basic steps. The common steps they use to do research and answer
questions are called scientific methods. Scientists often figure out questions to ask and answer just
by observing the world around them. What is a hypothesis? Forming a hypothesis (hi PAHTH us sus)
is a research method scientists use often. A hypothesis is an explanation for a question or problem
that can be tested. For example, imagine that the number of birds in an area decreased after snakes
came into the area. A scientist might make the hypothesis that the snakes were the reason the
number of birds decreased. A scientist who forms a hypothesis must be certain that it can be tested.
Before testing a hypothesis, scientists make observations and do research. The results of the
experiment will help the scientist answer whether or not the hypothesis is supported. Experimenting
To a scientist, an experiment is a test of a hypothesis by collecting information under controlled
conditions.
What is a controlled experiment? Controlled experiments involve two groups—the control group and
the experimental or test group. The control is the part of an experiment that represents the standard
conditions. In other words, the control receives no experimental treatment. The experimental group
is the test group that receives experimental treatment. For instance, imagine an experiment to learn
how fertilizer affects plant growth. Fertilizer would be used in the experimental group but not in the
control group. All other conditions—soil, light, and water—would be the same for both groups. In
this experiment, using fertilizer is the independent variable. The independent variable is the one
condition in an experiment that is tested. How much the plants grow is the dependent variable. The
dependent variable is the condition that changes because of a change in the independent variable.
Safety is another important factor that scientists think about when carrying out investigations and
experiments. It is important to know about dangers that may exist from doing an experiment before
you begin it. Anyone doing an experiment has a responsibility to follow safety procedures. They must
keep themselves and others out of danger. How are theories formed? The information gathered from
experiments is called data. A scientist carefully reviews or analyzes experimental results to decide if
the data supports the hypothesis. Scientists repeat their experiments in order to gather more data.
Data are considered reliable only when repeating the experiment several times produces similar
results. Scientists also compare the results of their experiments with the results of other studies.
They research published information in scientific journals and computer databases. It is important to
have details of an experiment presented in scientific journals and databases so scientists can
compare their results with those of similar studies. It lets other scientists test the results by repeating
the experiment. If many scientists get the same results, it helps support the hypothesis. A hypothesis
that is supported by many different investigations and observations becomes a theory
of things, they all use the same basic steps. The common steps they use to do research and answer
questions are called scientific methods. Scientists often figure out questions to ask and answer just
by observing the world around them. What is a hypothesis? Forming a hypothesis (hi PAHTH us sus)
is a research method scientists use often. A hypothesis is an explanation for a question or problem
that can be tested. For example, imagine that the number of birds in an area decreased after snakes
came into the area. A scientist might make the hypothesis that the snakes were the reason the
number of birds decreased. A scientist who forms a hypothesis must be certain that it can be tested.
Before testing a hypothesis, scientists make observations and do research. The results of the
experiment will help the scientist answer whether or not the hypothesis is supported. Experimenting
To a scientist, an experiment is a test of a hypothesis by collecting information under controlled
conditions.
What is a controlled experiment? Controlled experiments involve two groups—the control group and
the experimental or test group. The control is the part of an experiment that represents the standard
conditions. In other words, the control receives no experimental treatment. The experimental group
is the test group that receives experimental treatment. For instance, imagine an experiment to learn
how fertilizer affects plant growth. Fertilizer would be used in the experimental group but not in the
control group. All other conditions—soil, light, and water—would be the same for both groups. In
this experiment, using fertilizer is the independent variable. The independent variable is the one
condition in an experiment that is tested. How much the plants grow is the dependent variable. The
dependent variable is the condition that changes because of a change in the independent variable.
Safety is another important factor that scientists think about when carrying out investigations and
experiments. It is important to know about dangers that may exist from doing an experiment before
you begin it. Anyone doing an experiment has a responsibility to follow safety procedures. They must
keep themselves and others out of danger. How are theories formed? The information gathered from
experiments is called data. A scientist carefully reviews or analyzes experimental results to decide if
the data supports the hypothesis. Scientists repeat their experiments in order to gather more data.
Data are considered reliable only when repeating the experiment several times produces similar
results. Scientists also compare the results of their experiments with the results of other studies.
They research published information in scientific journals and computer databases. It is important to
have details of an experiment presented in scientific journals and databases so scientists can
compare their results with those of similar studies. It lets other scientists test the results by repeating
the experiment. If many scientists get the same results, it helps support the hypothesis. A hypothesis
that is supported by many different investigations and observations becomes a theory
