1. Evaluating Experiments
D. Crowley, 2008

2. Evaluating Experiments
Saturday, September 14, 2019Saturday, September 14, 2019
To be able to write an analysis and evaluation of an experiment

3. Height & Speed Experiment
An investigation was carried out to see how the height of a 1m ramp affects the speed a toy car can reaches when it rolls down
The results are shown below – work out the average time and the speed
Height
(meters)
Time taken to fall (seconds)
Speed
(m/s)
Test 1
Test 2
Test 3
Average
0.1
5.6
5.4
0.2
4.8
3.1
4.7
0.3
3.7
3.8
0.4
2.5
2.3
2.2
0.5
1.2
1.3
0.6
1.1

4. Height & Speed Experiment
Average (add up all the tests, and divide by the number of tests carried out)
Speed = distance ÷ time
Speed = 1m ÷ average time taken to fall
Height
(meters)
Time taken to fall (seconds)
Speed
(m/s)
Test 1
Test 2
Test 3
Average
0.1
5.6
5.4
5.5
0.18
0.2
4.8
3.1
4.7
4.2
0.24
0.3
3.7
3.8
0.27
0.4
2.5
2.3
2.2
0.43
0.5
1.2
1.3
0.81
0.6
1.1
0.83

5. Graph Your second task is to graph this data
How should we plot these results?
Remember, the variable you change goes on the x-axis (bottom), and the variable which was changed by the experiment goes on the y-axis (up side)
Make sure you use a ruler; choose an appropriate scale; make the graph big enough to read clearly; label and title the graph clearly

6. Graph

7. Speed & Height

8. Line Of Best Fit
Plot a line of best fit (a line that goes roughly through the middle of all the scatter points on a graph, ensuring the points are evenly distributed on either side of the line)

9. Reading A Graph
Identifying information from a graph is a key skill you must learn
To identify information from a graph, find the point you want along the x-axis (bottom) and draw a line up, until it hits the line of best fit, then draw a horizontal line across, so you can read the
For example, to find the speed when the ramp was 0.3m (green line)
To find the speed when the ramp was 0.55m (blue line)

10. Reading A Graph
For example, to find the speed when the ramp was 0.3m (green line); and the speed when the ramp was 0.55m (blue line)

11. Analysis Using your results and graph complete the analysis
Were the results accurate (how do you know)?
Was the equipment appropriate (did it ensure accuracy / could inaccuracies have occurred)?
Were there any anomalous results?
If there were anomalous results which were they, and how / why could they have been caused?
Was this test reliable?
Can you draw conclusions from these results?
How could you improve this experiment?

12. Levels
Level 4 – Graph mostly accurate, improvements and reasons for them suggested
Level 5 – Graph drawn and labelled correctly, analysis includes whether the results are accurate and why, improvements and reasons for them suggested. A scientific explanation for the results is given
Level 6 – Graph, axis and line of best fit correctly drawn, reasoned improvements given, accuracy of results explained and anomalies identified. Results are explained using key scientific words
Level 7 – Graph including scale and line of best fit accurate, reasoned improvements given. The accuracy of equipment is commented on for reliability. Anomalies have suggested explanations. Detailed discussion as to whether evidence makes a firm conclusion. Results are explained using scientific detail