Science Method - RD Flashcards
Variables
Things/factors which change during an investigation
Independent variable
- The variable that you choose to change
- The input variable
- The “cause”
Dependent variable
- The variable that you measure
- The output variable
- The “effect”
Fair testing and validity
Ensuring all other variables in an investigation are fixed so that you can fairly test the independent variable and how it affects the dependent variable.
Fixed variables
All other variables that could affect the output or dependent variable are fixed or kept the same throughout the investigation.
Accuracy
How close your measurement is to the true value you are trying to measure.
Precision
How similar the value your measurement is each time you repeat the measurement.
Reliable
How accurate and precise your measurements are.
Ensuring reliability
Ensure that your measurements are accurate and precise. To do this you need to repeat the process of measuring a number of times to be able to establish accuracy and precision. Generally, you need to report using the average or mean value.
Safety precautions
What could result in harm to humans or the environment? E.g. ensure lab safety rules followed. Be specific about the danger and the precaution required.
A hypothesis
A testable statement in the form of an “If… then… because statement.”
Conclusions
State whether the results support or do not support the hypothesis. Rewrite the hypothesis and give reasons where possible.
Bar graph
Used when the independent variable is in the form of category data e.g. colour, male vs female.
Line graph
Used when the independent variable is in the form of continuous data usually showing a particular change through time.
Scatter graph
Used when the independent variable is in the form of continuous data. Once multiple dots are plotted, trends can be spotted and samples can be compared. Sometimes a line of best fit is drawn (e.g. straight line or curve).
Pie graph
When you are representing the parts of a whole (e.g. percentages).
General placement of variable in a graph
Independent on the X-axis (horizontal)
Dependent on the Y-axis (vertical)
Working with the scale on a graph
- Use your ruler to draw check marks (typically every 1 cm for 10-15 cm)
- Look at the minimum and maximum values and ensure these fit onto the axis
- If not including 0 in your scale include a double line for the break in your axis
Labelling the axes
Ensure you name the variable and include the unit in brackets. e.g. time (seconds)
Suitable headings for graphs and tables
Must include both the dependent and independent variables in the description
Appropriate table layout
- Independent variable on the left and dependent on the right.
- Column headings include the units in brackets e.g. height (m).
- No units should be used in the cells - only values.
- Tables must be drawn with a ruler such that each cell has lines drawn around them.
