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Student's Guide to Scientific Skills (1 Viewer)

Green Yoda

Hi Φ
Mar 28, 2015
I have seen many people needing help including me for scientific skills such as first hand investigations and second hand investigations which are a major part of Internal assessments for many schools. I have researched and compiled a few key points which might help everyone.

First Hand Investigations

Students planning a first-hand investigation must consider issues related to accuracy, reliability and validity. This will impact on the choice of equipment and how confident they are about the conclusion drawn from the results of the investigation.

A valid experiment is a fair test. A method is valid if:
• It investigates what you think it will investigate (i.e. the procedure actually tests the hypothesis and the experiment includes an appropriate range of values).
• It incorporates suitable equipment (e.g. measuring cylinder to measure volume rather than a beaker).
• Variables are controlled.
• Appropriate measuring procedures are included.

Discussions about validity must:
• Identify what validity is.
• Identify the factors that affect validity of the particular experiment you are considering (the variables that must be controlled, appropriate equipment, the range of values etc).
• Assess the overall validity of the experiment.

A reliable experiment has results which can be obtained consistently. To ensure the results are reliable:
• The experiment must be repeated and consistent results must be obtained (within an acceptable margin of error).

* The experiment should be repeated at least twice (i.e. carried out three times) and the results averaged. This ensures that the effect of random error is minimised or that the outliers can be disregarded or removed. Random errors are errors that might affect your experiment the first time you do it but not the second or third time for example.

Note: Measurements can be reliable without being valid. However they cannot be valid unless they are reliable.

Discussions about reliability must include:
• Identify what reliability is.
• Identify that reliability is increased by repeating the experiment and averaging the results.
• Identify that this minimises the effect of random errors/outliers and/or allows them to be removed or disregarded.
• Give examples of possible random errors that may have crept into the experiment you are considering.
• Assess the overall reliability of the experiment.

Accuracy depends on the design of the experiment (i.e. the validity of the method) and the sensitivity of the instruments used. Results are accurate of:
• They are close to the true value of the quantity being measured.
• They can be substantiated in secondary sources.

Note: Accuracy is important by making the experiment as valid and reliable as possible.

Second Hand Investigations

Students are often asked to "identify date sources, gather, process, analyse and present information from secondary sources", when researching information using articles, journals, mass media, textbook, etc.

To consider if the information gathered is valid, you must consider and e
• The author's of the article's credentials (i.e. is the author qualified in this area). For example, was the author a teacher, a scientist in that field.
• Whether the purpose of the article is not resulting in bias.
• Whether the site or publication is reputable (i.e. government site, textbook, etc).
• Whether the data was gathered using appropriate method and measuring devices.
• Whether it is current.
• Whether the information relates to the problem or hypothesis being investigated.

That means if your information is current, written by an expert in the area you are investigating, without bias and is from a reputable source, then the information can be considered valid.

To determine if the information you are gathering is reliable, you must consider and evaluate the following:
• Whether the information you are gathering comes from more than one VALID SOURCE (i.e is the information consistent with the information from other reputable sources?)

That means if you can find similar information in at least two valid sources, then your information can be considered reliable.

To ensure secondary sources are accurate, the information from the source must be both VALID and RELIABLE. E.g If similar information comes from a variety of reputable sources such as Scientific Journals and Government Sites it is considered to be accurate.

Other Scientific Skills
Independent Variable: Only thing you change.
Dependent Variable: What you measure.
Controlled Variable: What is kept the same.

For GRAPHS remember to:
• Title the graph
• Correctly label the axis
• x-axis=Independent variable
• y-axis=Dependent variable
• Scale on each axis must have correct identified units
• Scale must be uniformly increasing

• Title for the table
• Independent variable must be either first column or row.
• Dependent variables can go in the rest of the column or rows.

Hope this helped! Good luck in your scientific endeavours :)
Last edited:


Apr 14, 2015
Might also be helpful to know about extrapolation and interpolation.
They might ask the validity of predicting results outside/inside the given values after drawing a line of best fit.

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