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Report Writing

The Aim

What is the objective of your experiment?

An aim describes what you will be investigating e.g. “The aim of this experiment is to investigate the relationship between ____ and ___.”

The Hypothesis

A prediction for the outcome of the experiment

A hypothesis should make a specific and testable prediction about the outcome of your experiment. Remember, you should change only one variable, but you can measure more than one variable.

E.g. I think that _______ will [increase/decrease] when the ______ is [increased/descreased].


Independent Variable: The variable that you will change.

Be specific about your description and units. E.g. We will change the concentration of the $HCl$ measured in $mol$.

Dependent Variable(s): The variable(s) being measured.

You can measure multiple variables, but generally only measure one. Be specific about what you will measure and the units the measurement will be gathered in.

E.g We will measure the time taken to produce $10ml$ of carbon dioxide gas.

Control Variable(s): Things that you are keeping constant in between trials.

E.g. The concentration of the $HCl$ used, the volume of $HCl$ used, the test tube used, the timer used, the same person using the timer


Reliability and Validity

What does it tell you?The extent to which the results can be reproduced when the research is repeated under the same conditions.The extent to which the results really measure what they are supposed to measure.

How is it assessed?By checking the consistency of results across time, across different observers, and across parts of the test itself.By checking how well the results correspond to established theories and other measures of the same concept.

How do they relate?A reliable measurement is not always valid: the results might be reproducible, but they’re not necessarily correct.A valid measurement is generally reliable: if a test produces accurate results, they should be reproducible.


Trial 1Trial 2Trial 3Average
Small Chips
Large Chips

Average: Add up all your trials and divide by the number of trials.