Unit 3 - Science Investigation Skills

Question 1

What is a hypothesis?

Answer 1

A hypothesis is a prediction that can be tested using experiments. It is based on observations or a scientific theory.

Question 2

What should you include in a hypothesis?

Answer 2

• What you’re going to change.

- What you’re going to measure or calculate from your measurements.

Question 3

What is a null hypothesis?

Answer 3

It is when you predict that there will be no link between the variables

Question 4

What are the types of hypotheses?

Answer 4

• If/then statements e.g. if more water is added to the soil then the plants will grow more.
• One variable is dependent on a second variable e.g. the growth of a crop is dependent on the type of fertiliser in the soil.

Question 5

What are the types of variables?

Answer 5

• Independent variable - variables that we change - you can only change one variable to test a hypothesis.
• Dependent variables - variables that we measure and investigate. (dependent variable depends on independent variable).
• Control variables - variables that we keep the same - same as independent variables, once you decide the independent variable then the rest become control variables. You need to state how you will control these variables.

Question 6

What should you include when planning an investigation?

Answer 6

You will need to include:

• Appropriate equipment e.g. choose the smallest measuring equipment to measure the volume; more accurate.
• Appropriate techniques
• Standard procedures

Question 7

How should you choose appropriate equipment for an experiment?

Answer 7

You should include:

• What is it for?
• How many do you need?
• How precise does it have to be?
• What size does it have to be?

Question 8

How should you choose appropriate techniques for an experiment?

Answer 8

You should include:

• What are you investigating?
• What method are you using?
• Do you have the equipment available to carry out the technique?
• Do you have enough time to carry out the technique?
• Do you have the skills/knowledge to carry out the technique?

Question 9

What is qualitative data?

Answer 9

It refers to the appearance or value of something, e.g. color observed or whether bubbles are produced.

Question 10

What is quantitative data?

Answer 10

It refers to numerical measurements, e.g. volumes and times measured.

Question 11

What is the standard operating procedure (SOP)? Why should you follow SOP?

Answer 11

It is an established procedure or method used to carry out a routine activity.
Following an SOP, ensures consistent results every time the activity is carried out.

Question 12

Why are risk assessments done?

Answer 12

Risk assessments are done to:

• identify hazards
• evaluate the risks associated with those hazards
• determine ways to eliminate or control those risks

Question 13

What is the difference between hazards and risks?

Answer 13

• Hazards = the equipment or substance that can cause harm e.g. hot plate or hydrochloric acid.
• Risk = the harm that the hazard could cause and the chance of it happening e.g. hot plate can cause skin burns or hydrochloric acid can cause skin corrosion or chemical burns.

Question 14

Produce a risk assessment table.

Answer 14

Check revision guide pg 52 for example.

Question 15

What should a method include?

Answer 15

A method should:

• be a step-by-step set of instructions.
• be logically ordered.
• allow you to take sensible measurements.
• allow you to test your hypothesis.

Question 16

What should you consider when planning your method?

Answer 16

You need to think about:

• what you’re testing
• what you want to measure
• how you’re going to measure
• what technique you will use
• what variables you must control
• how many repeated readings you will take
• what you are going to do with the data

Question 17

What should you consider when recording data?

Answer 17

You should consider:

• results from calculations should be the same precision (number of decimal places or significant figures) as the averages.
• anomalous results should be repeated if possible and not used in calculations.
• a range of 3 results allows for a valid graph to be produced.

Question 18

How should you inference from observations/measured results?

Answer 18

You can comment on:

• colors
• smells
• solids produced/dissolving
• gases produced

Question 19

What are the types of data?

Answer 19

• Continuous data e.g. age of the plant
• Discrete data e.g. number of plants
• Some data is a mixture of numbers and names e.g. number of different types of plants found in a garden.

Question 20

What are the ways of processing data?

Answer 20

For example:

• mean and standard deviation
• error bars
• statistical tests
• use of formulae
• conversion of units
• standard form
• percentage error in measuring equipment

Question 21

What are line graphs and bar charts used to present?

Answer 21

• Continuous data is displayed on a line graph.

- Bar charts are used for discrete data and can compare different sets of data.

Question 22

What should you consider when displaying data?

Answer 22

You need to think about:

• what type of data is it?
• what type of chart or graph is appropriate?
• use appropriate scales
• plot data correctly
• draw a smooth or curve line
• use all of the graph paper
• label both axes correctly and with units.

Question 23

Define:

• Patterns
• Trends
• Conclusion

Answer 23

• Patterns = the shape of the graph.
• Trends = the relationship between factors on the graph or in the table.
• Conclusion = how well your results support your hypothesis.

Question 24

What must you do when identifying a pattern or trend?

Answer 24

You must:

• describe the whole graph/chart
• ignore any anomalous plots
• describe changes in the pattern/trend across the graph.

Question 25

What are primary and secondary data?

Answer 25

• Primary data = data collected for yourself using experiments and investigations.
• Secondary data = data collected by someone else from primary sources e.g. researching in books, scientific papers.

Question 26

How to draw a conclusion from your experiment?

Answer 26

• To draw a conclusion, compare the primary and secondary data.
• If they don’t show the same patterns/trends, you must question:
• did you use the same method?
• if not, is one method better than another?
• was the secondary data a larger data set?
• is the hypothesis correct?

Question 27

How to make improvements to the investigation?

Answer 27

• You can consider your:
• equipment
• reactants
• methods
• techniques
• You need to explain how your investigation was valid and explain any changes you could make to improve your investigation.

Question 28

What are the sources of errors?

Answer 28

• Systematic error = an error that is built into the method or equipment you’re using e.g. a balance that is not calibrated so you will get an identical error every time you use it.
• Random error = errors made when not following the method correctly. minimised by repeating results and taking averages.
• Misreading of observations = can cause qualitative errors e.g. observing incorrect colour in flame test.

Question 29

What should you consider when carrying out an evaluation?

Answer 29

You must consider :

• Accuracy = is the data close to the true value? e.g. error due to equipment means less accurate results.
• Reliability = how trustworthy your data is i.e. ensured by repeating readings to find anomalous results.
• Precision = how close repeat readings are to each other i.e. improved by using measuring equipment that measures to more decimal places.

Question 30

What should you include when explaining strengths and weaknesses?

Answer 30

• In evaluation, you must include strengths and weaknesses:
• How did your method/equipment/standard procedure/technique ensure you got reliable results?
• How might the method/equipment/standard procedure/technique cause errors?
• Make sure to include improvements for those strengths/weaknesses.