ISA - Section 1

Question 1

Explain why you made this hypothesis

Answer 1

State hypothesis

Clear scientific explanation

Question 2

Describe in detail how you are going to carry out your investigation (9 marks)

Answer 2

Equipment with resolutions
Diagram of how to set up equipment
Clear step-by-step method
I.V with range, interval, resolution and unitd
D.V with resolution and units
2 C.Vs with how to control and why you control
Fair test (see card)
Risk assessment with hazard, risk, level and control

Question 3

How do you answer fair test part of question 3?

Answer 3

I will make my experiment by making sure the “control variables” are kept the same throughout the experiment
If I changed these factors, the “dependent variable” would also change

Question 4

What do you include in the table?

Answer 4

Two columns with I.V and D.V with units

Question 5

Compare the usefulness of the 2 sources

Answer 5

Give a positive of each source

Why was one not as good?

Question 6

Why are repeated readings a good idea?

Answer 6

Find and discard anomalous results
Calculate a mean by adding all repeats and dividing by the number of repeats
Check how precise results are
Check for repeatability (just to be sure)

Question 7

Name on variable you will need to control

Describe a preliminary investigation to help you find the best value for this variable (NOT COMPLETE)

Answer 7

Name control variable

Brief but clear investigation (different values for C.V with highest and lowest I.V value

This value gives the biggest difference between the lowest and highest value of the I.V so I will use this value

Question 8

Explain advantages of sharing results with others

Answer 8

Allows you see any similarities or differences in the pattern
Allows you to calculate more accurate mean and reduce effect of random errors
Allows reproducibility to be confirmed

Question 9

Outline one other method you could have used (NOT COMPLETE)

Answer 9

Brief but clear method

Why wasn’t it chosen

Question 10

It is better to repeat measurements 3 times and then calculate a mean. Explain how this will lead to a more accurate answer.

Answer 10

Enables you to spot and discard anomalous results so that they don’t affect the pattern
Enables you to calculate a mean and reduce the effect of random errors

Question 11

What are the control variables and how and why do you control them?

Answer 11

Permanent / temporary - always use water with sulphate salts - the temporary and permanent hard waters need different amounts of soap solution to form a lather

Amount of hard water - measure out 10cm^3 of the water sample with the measuring cylinder before pouring into the conical flask - if there is more water, it would take more soap solution to form a lather

Type of soap solution - always use Wanklyn’s soap solution - a different type of soap might be able to take in different amounts of ions meaning that the amount of soap solution added to form a lather would differ