This document provides a comprehensive overview of the practical skills required in science exams, covering topics such as planning experiments, implementing procedures, analyzing data, and evaluating results. It offers detailed guidance on best practices for presenting observations, interpreting g...
Practical skills
Practical skills will be tested in the written examination.
Planning may involve:
● solving a problem in a practical context
● selection of suitable apparatus, equipment or techniques
● describing a method or technique
● application of scientific knowledge
● identification of all variables
● evaluation of the method
Implementing may involve:
● describing how to use a wide range of practical apparatus and techniques
● suggesting precautions that should be taken to ensure results are valid
● assessing the hazards and potential risks involved
deciding on appropriate units for measurements
presentation of observations and data in an appropriate format (table)
Analysis may involve:
● processing qualitative and quantitative experimental results
● interpreting qualitative and quantitative experimental results
● using appropriate mathematical skills
● using significant figures appropriately
● plotting and interpreting suitable graphs from experimental results, including (i) selection
and labelling of axes with appropriate scales, quantities and units, and (ii) measurement
of gradients and intercepts
● drawing conclusions from data
Evaluation may involve
● identifying anomalies in experimental measurements
● identifying limitations in experimental procedures
● understanding the meaning of precision and accuracy in the measurement of results
● appreciating the margin of error, percentage errors and uncertainties in apparatus
● calculating the standard deviation of a data set
● assessing the reliability of data using range bars and error bars
● calculating percentage error
● suggesting improvements to experimental design, procedures and apparatus
● assessing the validity of data
Your ability to apply your knowledge to practical situations will be tested. This includes
questions that test your skills in:
● Planning
● Implementing
● Analysis
, ● Evaluation
Planning
● You may need to solve a problem set in a practical context.
● You may be asked to make a prediction from a given hypothesis, or you may be given a
prediction and asked how you could test it.
● You should be able to consider the prediction and outline an experiment or investigation
that will test the prediction. For example:
If you are given the prediction that yeast will stop respiring at 45°C, how would you test it?
You would need to describe how you would determine when respiration was taking place and
how you would determine when it stops. You should then describe a method in which you tested
yeast at a range of temperatures around 45°C to determine at what temperature it actually stops
respiring.
1. Suitable apparatus, equipment and techniques
Select apparatus from a range of normal glassware and chemical reagents.
As respiration in all organisms releases carbon dioxide, it would be sensible to arrange a test
that demonstrates the presence of carbon dioxide such as using lime water or bicarbonate
indicator. You would then place a sample of yeast at different temperatures and demonstrate
that it produces carbon dioxide at some temperatures but not at others.
You need to select apparatus that enables you to change the temperature of the yeast sample
and pass the gas produced through the selected reagent.
Draw a diagram of the apparatus and how it is set up.
Application of scientific knowledge
1 Your plan should be based on suitable scientific knowledge. This knowledge should be
applied to the practical context you are planning.
2 You will need to show that you understand the process of respiration well enough to know that
sugars are needed and carbon dioxide is released. The process involves enzymes and it is
these that are affected by the change in temperature.
Identification of variables
1 The independent variable is the variable you choose to change during the experiment.
Temperature is the independent variable in this example.
2 The dependent variable is the variable that changes as a result of changing the independent
variable. Production of carbon dioxide is the dependent variable in this example.
3 Controlled variables are any other factors that might affect the result, such as pH, volumes of
solutions used, concentrations of solutions used.
Evaluation of the method
Show that you have considered whether the method is appropriate to test the desired
hypothesis. Ask questions about the method.
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