1. AQA Science B Controlled
Assessment
Learning Objective: Revise the key
areas included in the Science
controlled assessment unit

2. Guide to the CA
Section Marks Awarded Slide Pictogram
1: Research 4
2: Planning 8
3: Managing and Assessing 8
Risk
4: Collecting Data 8
5: Processing Data 10
6: Analysing Data 6
7: Evaluating the Practical 6
Activity
Total 48

3. Starter: Match the Keywords
Aim How will you carry out your experiment?
Dependent Variable What are you trying to find out?
Method What are you deliberately changing in your experiment?
Control variable What equipment will you use?
Independent Variable What are you going to measure?
Prediction What variables will you keep the same?
Based on scientific knowledge what do you think the
Apparatus
relationship is between the dependent and Independent
variables

4. Constructing Aims
The purpose of my experiment is to
investigate…………………...................................
Writing Frame (a statement discussing the effect of the
independent variable on the dependent
variable)
To gain the full marks in this area you must mention both the independent and dependant
variables
i.e.
Aim: To measure the effect of changing the temperature on the rate of a chemical
reaction by timing how long it takes the cross to disappear with different
temperatures of Sodium thiosulphate are reacted with hydrochloric acid .

5. Methods
BAD GOOD
I filled half of the crucible 1. Half fill the crucible with
with alcohol. Then I put alcohol.
50ml of water in the beaker 2. Put 50ml of water in the
and measure the beaker and measure the
temperature. I then set up temperature.
the equipment as shown in 3. Set up the equipment as
the diagram and put my shown in the diagram.
goggles on. I lit the alcohol
and burned for 5 mins. I 4. Put your goggles on.
measured the temperature 5. Light the alcohol and burn
and recorded it in the table. for 5 minutes
6. Measure the temperature
and record in the table.
Think of your method as a recipe. It should be a set of clear
steps in a PASSIVE VOICE.

6. Identifying Variables
1. Finding the effect of string length on the time
of pendulum swing.
2. Finding how the number of coils affects the
number of clips that the electromagnet can
pick up.
3. Measuring the temperature of water as it is
being heated.
4. Investigating the effect of different types of
exercise on pulse rate.
5. Investigating the effect of Caffeine on a persons
reaction time
Identify the INDEPENDENT, DEPENDANT and 2 possible CONTROL variables for
each experiment

7. Predictions: Describing relationships
As ……… (independent) increases/decreases
Writing Frame: ……… will increases/decrease (dependent)
because………………….. (scientific knowledge)
To gain the full marks in this area you must link the independent and dependant variables
and use information from your research to support your “educated guess”
i.e. Aim: to measure the temperature of water as it is being heated.
Prediction: As the time the beaker is over the Bunsen increases the temperature of
the water will increase until the temperature of the water reaches 100oC as this is
the boiling point of water. Initially the temperature will increase because as the
water particles are heated they vibrate faster, their kinetic energy is transferred
into heat energy. However once their boiling point is reached they have enough
kinetic energy to change state from liquid to a gas, so steam will be produced.

8. Managing and Assessing Risk
Place all of your apparatus in Equipment/Ch Hazard Risk Control
emical Measure
table and use your own
knowledge and HAZCARDS to Magnesium Irritant: Can Medium as it Clear up
sulphate damage skin can be spilt spillages
complete (0.1M) cause slips easy and immediately
or falls if looks like using paper
Apparatus (Equipment) spilt water so you towels. Wash
Magnesium sulphate (0.1M) might forget hands after
to wash it off practical,
Zinc sulphate (0.1M)
wear goggles
Test tube rack
Zinc sulphate
4 test tubes (0.1M)
measuring cylinder
Spatula Carrying out
Electronic balance the
experiment Look at the full example
Tin
that your teacher shows
Iron Glassware
you.
Electronic
balance
Don’t forget to record the Tin
sources that you use
Iron

9. Drawing Tables
Independent Dependant Variable (Units)
Variable
(Units)
1 2 3 Mean
Exclude any anomalous repeats when All data to 2 Decimal Points
calculating the mean. Make sure you show
which ones have been excluded.
This is the standard table. You may need a slightly different one if you are not doing repeats

10. Bar Charts – Categoric Data
Title
Graph showing the mean reaction times of
No marks
4 students Straight lines for
but
5 plotting
essential
4
Dependant Variable e.g.
Mean Reaction Time (s)
3 Key
Correctly Reaction Time
labelled, appr 2 (s)
opriately Even bars
scaled Y axis 1
with units
0
Kate Mary Bob Peter
Independent variable e.g. Pupil
N.B. The title of the axes
Correctly labelled appropriately scaled Are the same as the
X axis with units Headings of the table!!

11. Line Graph – Continuous Data
Title
No marks Graph showing the mean temperature Clear
Dependant Variable e.g.
but change (oC) over 40s plotting
Mean temperature (oC) 50
essential
40
Key (if needed)
30
20 Column1
10
0
Line of best
10 20 30 40
fit
Correctly
labelled Independent Variable e.g. Time (s)
appropriately
scaled Y axis Correctly labelled, appropriately scaled X
with units axis with units
N.B. The title of the axes
Are the same as the
Headings of the table!!

12. Processing Data: Comment on the
Graph
Describe what your graph shows. Make a link between the independent and
dependent variables. Does it match your prediction. Make direct reference to parts
of your graph by quoting numbers/points from it.
Increase
Decrease
Writing Frame
Directly proportional
Keywords:
Linear
Stays the same
Double
Halved

13. Analysing Data
Step 1: What are the findings of your experiment? Use an ER statement i.e. The
smaller the wood the quicker it burns
Step 2: Explain your ER Statement using information from your experiment to back
it up
Step 3: Compare your results to the results from the secondary data do they
support/contradict your conclusion? How?
Step 4: What are the limitations of your primary and secondary data? How could
you overcome this?

14. Evaluation
Step 1. Comment on the practical, was your method good? Did it enable you to
collect valid results? Did you have any anomalies? What did you do about it?
Strengths Weaknesses
Step 2. Evaluate your working
methods. What were your
strengths and weaknesses
Improvements to be Reasons
Step 3. What improvements made
could you make and why would
this be of benefit?

15. Step 1
Comment on
I did lots of repeats to make sure that I could
reliability ignore any anomalous results
Tips for your Evaluation
The experiment was valid because there was only
one independent variable, the pH and everything
Comment on
else, like the light and temperature was controlled.
Validity and fair
testing I used the same number of seeds and volume of
solution in each test so that it was fair.
Step 2
Improvement for
getting more data I only looked at the height of the cress seedlings. I
could have measured the width and colour of the
leaves as well.
Improvement for The heights were all very small, so if I measured
getting better them over a period of several weeks, I could see if
data the pH affected the growth over a period of time.
I could also have seen if pH slowed down
Improvement for germination, rather than stopped it.
greater accuracy
I could have made it more accurate by using
vernier calipers to measure the height of the
seedlings.

16. Lastly: Quality of Written
Communication
Level Key Points (get up to 6 extra marks)
1 Knowledge of basic information
Simple understanding
Answer is poorly organised with few keywords .
Spelling, punctuation and grammar is weak
2 Knowledge of accurate information
Clear understanding
Answer has some structure, some keywords used but not always
accurately.
Spelling, punctuation and grammar is reasonably accurate.
3 Knowledge of accurate contextualised information
Detailed understanding supported by evidence
Sequenced, structured and organised answer with appropriate
use of keywords
Spelling, punctuation and grammar is faultless