 # The Scientific Method

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A series of free Science Lessons for 7th Grade and 8th Grade, KS3 and Checkpoint Science in preparation for GCSE and IGCSE Science.

The following videos explain the steps of the Scientific Method
2. Planning and Recording
3. Analyze, Conclude and Evaluate

Planning investigations
• The plan is like a recipe.
• Describes the equipment and materials to be used and what to do with them.
• Measurements made in an investigation is called data.
• Collect data that is accurate and precise.
• accurate data is close to the true value of what you are trying to measure.
• precise data gives similar results if you repeat the measurement.
• the spread of sets of repeat data is small if precise data is collected.
• measurements have some uncertainty because of the instrument being used.
• When the same investigation is repeated several times, the data should be similar = repeatable.
• If other groups do the same investigation, they should get data that is similar = reproducible.
• types of data
- continuous - it can have any value, such as length or temperature.
- discrete - it can have only whole-number values.
- categoric - the value is a word such as 'red' or 'cold'.
• how many measurements?

What a plan should include?
• The scientific question you are trying to answer.
• The independent and dependent variables.
• A list of variables to control and how you will do it.
• A prediction: what you think will happen and why.
• A list of the equipment you will need.
• A risk assessment.

Exercise:
Does the temperature of water affect the mass of salt that dissolves in the water?
Write a plan to investigate this.

Recording Data
• We usually collect data in a table.
• Drawing a graph or chart will help you see patterns in the data.
• Each time you change your independent variable, you should take repeat measurements of your dependent variable.
• You should check your data for outliers. An outlier, or anomalous result, is very different from the others. Repeat the measurement to replace the outlier. Do not include the outliers when calculating the mean.

What kind of graph? • If both independent and dependent variables are continuous, then you should plot a line graph.
• If the independent variable is categoric, you should plot a bar graph or pie chart.
• For both line graphs and bar charts, plot the independent variable on the x-axis and the dependent variable on the y-axis.

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.  