1. Complete the risk assessments
Hazard
Risk
Control measures
Hot apparatus (eg. tripod, bench lamps)
Use with care on a tile. Cut away from fingers.
Water and electrical equipment (eg lamps)

2. ANSWERS: Risk assessments
Hazard
Risk
Control measures
Hot apparatus (eg. tripod, lamps)
Skin burns
Touch cool base only
Sharp scalpel
Cut skin
Use with care on a tile. Cut away from fingers.
Water and electrical equipment (eg lights)
Electric shock
Dry hands before touching switch.
Keep water well away from plug/switch

3. Hypothesis tips
A hypothesis states what you think is going to happen in the experiment.
A hypothesis should link the independent and dependent variables.

4. Hypothesis practise
“A student did an investigation to see the effect of different amounts of fertiliser on leaf size in bean plants.”
What is the independent variable?
What is the dependent variable?
Write a hypothesis for this experiment.

5. Hypothesis practise
“A student did an investigation to see the effect of different amounts of fertiliser on leaf size in bean plants.”
What is the independent variable? Amount of fertiliser
What is the dependent variable? Leaf size
Write a null hypothesis for this experiment. “The higher the amount of fertiliser, the larger the bean leaf size”

6. Explaining your hypothesis
“The higher the amount of fertiliser, the larger the bean leaf size”
Explain the hypothesis….

7. Explaining your hypothesis
“The higher the amount of fertiliser, the larger the bean leaf size”
Explain the hypothesis….
Plants will absorb the mineral ions in the fertiliser through their roots and use it to help make new proteins, allowing them to grow.

8. Graph tips
Use an even scale that allows you to plot accurately to nearest 1mm (avoid scales like 0, 7, 14, 21 OR 0, 3, 6, 9, 12)
Each scale should occupy at least 1/3 of the paper.
Show clear headings and units (note m is NOT suitable for minute)
Draw a suitable line (if the data is continuous)

9. New info’
Sketch graphs
A sketch graph can be drawn to show the basic pattern present in your data….
Rate of reaction
Temperature

10. Sketch graph tips Full headings on each axis. Units are not required
New info’
Sketch graph tips
Full headings on each axis.
Units are not required
No scale values are needed
Draw the line carefully, so that the trends in the data are clear.

11. Draw a sketch graph of these results
apply
Draw a sketch graph of these results
Carbon dioxide added / %
Time for lettuce to grow to harvest size / days 52
0.2 41
0.4 32
0.6 29
0.8
Extension: How can a farmer boost carbon dioxide levels in a greenhouse?

13. Discuss in your groups where the 3 marks will be awarded.
recall
Were there any anomalies? Explain your answer. (3 marks)
Discuss in your groups where the 3 marks will be awarded.

14. Were there any anomalies? Explain your answer.
1. Anomalies are points that do not fit the pattern.
2. They lie away from the line of best fit.
3. All points lie on the line, so no anomalies are present.

15. Discuss. What key difference would be in your answer if the graph looked like this?

16. Were there any anomalies? Explain your answer.
Anomalies are points that do not fit the pattern.
They lie away from the line of best fit.
The point at 0.5 % CO2 is far from the line of best fit, so is an anomaly. (The time to grow was too long, 40 days instead of 30).

17. How to use repeat readings
New info’
How to use repeat readings
Often during an investigation, if there is time, you will carry out repeat readings.
Repeat readings can be used to help identify and remove anomalies.
This allows the calculation of the mean.

18. Use the repeat readings to get more accurate results.
Temperature of reaction / °C
Time for reaction /sec
Test
Repeat 1
Repeat 2 20
200
210
207 30
158
162
168 40 45
110
117
apply

19. Using repeat data to get more accurate results
Temperature / °C
Time for reaction /sec
Mean time .…/ sec
Test 1
Test 2
Test 3 20
200
210
207
206 30
158
162
168
163 40
(45)
110
117
114