Scientific Method / Lab Investigation Reports

Scientific Method / Lab Investigation Reports
The following are general guidelines for lab reports. A great deal of this should be review to you, but I
may have some specific guidelines that are unfamiliar to you. We will discuss these as we conduct our
labs, but ultimately it is your responsibility to be familiar with these terms when you are asked to write a
lab report. You may also use the rubric for your specific lab assignment which gives more detail about
the parts of the scientific method.
The following may also serve as a resource:
The question should ask what we are trying to figure out in a scientific experiment. This question should
guide you as you conduct your experiments and gather information.
 Example: “Which freezes faster – fresh water or salt water?”
This is your prediction of the outcome of the question. This should be based on observations and previous
knowledge or experience. In other words, you don’t have the facts to back up your hypothesis yet, but you
have a pretty good idea. It must be something that can be tested. This ends up serving as a rough outline
of how your experiment should be performed. Always written as an “if _____, then ________”
statement. No explanation is required.
 Example: “If I add salt to fresh water, then the water will take longer to freeze”
INDEPENDENT VARIABLE (also called manipulated variable)
A variable is ay factor that you can change in an experiment. Your independent variable is what you are
changing on purpose. Always identified in the hypothesis in this format: “If (Independent Variable), then
____________” All other variables should remain constant or unchanged.
 Example: amount of salt
DEPENDENT VARIABLE (also called responding variable)
A variable is ay factor that you can change in an experiment. Your dependent variable is what you are
trying to find out. The dependent variable is always reacting or responding to changes you have made in
the independent variable. Always identified in the hypothesis in this format: “If ___________, then
(Dependent Variable)”. All other variables should remain constant or unchanged.
 Example: temperature of water
A variable is any factor that might have an affect on the outcome of your experiment. A variable that is not
changed, or is kept constant in an experiment is called a constant. In a good experiment, most things are
kept constant so that you can test only the dependent and independent variables.
 Example: We did the experiment in the same place, so the location is a constant – it did not
Sometimes we keep an example of something that we did not change, just to use for comparison. This is
referred to as our control. This is not always included in every investigation
 Example: Regular fresh water (no salt added)
List all materials used in the lab.
This is a step-by-step detailed plan of everything that is done during the experiment. Complete sentences
are used. This should be written so that someone else who knows nothing about your experiment could
pick up your procedure, follow the directions and complete the experiment.
 Example:
1) Fill two 200 mL beakers with fresh water
2) Add 1 tsp of salt to one beaker
3) Place both beakers into the freezer
All experiments will include at least one type of evidence, and usually both of them. The 2 types are:
Qualitative Observations = What you can hear, taste, smell, see, or touch. (use all your senses)
 Example: I noticed that the salt made the water look cloudy before it completely dissolved into
the water
Quantitative Observations = These require measurements. These are numbers which may be included in a
chart, graph, or table depending on the type of experiment.
 Example: A data table that includes the time it takes for water to freeze in both beakers.
This is the answer to the question you created at the beginning of the experiment. First go back to your
hypothesis and re-state it, adding whether or not it was supported by the evidence. Don’t ever say if it was
correct or incorrect. You need much more data before this could ever be proven. You are only speaking of
your particular experiment.
 Example: “My hypothesis, ‘If I add salt to fresh water, then the water will take longer to freeze’
was supported by the data.”
Now, you may begin listing your evidence in full sentences and explain why your data supports or does not
support your hypothesis. This section is at least one paragraph long. Usually makes use of new
vocabulary learned during the experiment or current chapter.
Here you explain either what went wrong or what could have gone wrong (no one is perfect – it’s likely you
made some mistake even if you don’t think so) during your experiment and explain the result it would
have had upon your data.
 Example: “Our salt water and fresh water were put in freezers that were two different
temperatures. As a result of this, we could not tell if the fresh water froze faster only because it
was at a lower temperature”