# How do we know what we know

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```					  “How Do You Know
What I Know?”
Matthew Sender
Mentor: Dr. Grant Krow
Teacher: Maria Fitzgerald
First Step, Proper Data Collection
What data should we collect?
The data you collect should allow you to
answer the question you are investigating.
How should we collect our data?
Proper data collection is methodical, rather
than haphazard.
A Record Book Is Essential!
Plan your experiment before you begin

This includes:
Record Book
• What materials you will need
• Step by step procedural guide
• Space to record your observations

Just like your school lab book

The big difference is that you are designing
the experiment
How Do You Investigate a Question?
• Questions are investigated by careful control
of the experimental conditions such that only
“the thing” being studied is changing.
• Another essential piece is to have a control
experiment.
– A Control experiment is one in which the
experiment is carried out without including the
variable.
Accuracy of Our Data?
• In order to assess the precision of our data we
need to run each experiment more than once
• Optimally 3-5 times for each experiment

• In order to properly assess the accuracy of our
data we need to know the “true” value of
whatever we are measuring.
How Do We Represent Our Data Now
That It Is Collected?
Figures and Tables!
- Figures, such as graphs, are very effective at
showing trends and relationships
- Figures, such as diagrams or pictures, are
effective at showing visual data, or
experimental apparatus
- Tables are very effective at showing values for
comparison.
An Example: Heating Curve of Water
Time    Temperature                         Heating Curve of Water
120
0:00        23

1:25        31
100
2:50        42

4:30        53
80
5:38        60

6:55        70        60

8:12        80
40
9:32        90

11:00       100
20
12:42       103

14:41       103        0
0:00   2:24   4:48   7:12   9:36   12:00   14:24   16:48   19:12
17:41       103
Let’s Spice It Up
Question to be studied-
What is the effect of flame height on the
heating curve of water?

What do we have to do so that we collect
quality data to answer our question?
Materials   Method   Data
Materials                  Method                          Data
1.   Add 50 mL of water to
• Stopwatch                     cup
To Record:
• Heatable cup with        2.   Light Bunsen burner and    Flame Height,
volume markings               adjust flame to 4 inches   Trial ,Time,
• Ruler                    3.   Place cup 5 inches from        Temperature
top of Bunsen burner
• Bunsen burner
4.   Record temperature
• Gas supply                    every minute until the
• 1 L of bottled water          temperature is constant,
• Stand                         then continue to heat
and observe for 3
• Clamp                         minutes.
• Thermometer              5.   Repeat 2X, then repeat
flame height to 5 and 6
inches

How many variables in our method can we find? How many are we changing?
Fake “Collected” Data
Flame Height 6”                            Flame Height 5”
Flame Height 4”
Trial 1 Trial 2 Trial 3 Average            Trial 1 Trial 2 Trial 3 Average
Trial 1 Trial 2 Trial 3 Average
Min     Temp Temp Temp Temp                Min     Temp Temp Temp Temp
Min     Temp Temp Temp Temp
1.1     23       23     23        23       1.1     23       23     23        23
1.1      23       23     23       23
2.1     42       43     41        42       2.1     36       37     38        37
2.1      31       30     33       31
3.3     60       61     61        61       3.3     51       53     52        52
3.3      42       43     41       42
4.2     80       81     81        81       4.2     66       68     67        67
4.2      53       53     53       53
5.4 100         101 100          100       5.4     82       81     81        81
5.4      60       61     61       61
6.4 103         103 103          103       6.4     97       96     97        97
6.4      70       71     71       71
7.3 103         103 103          103       7.3 103         103 103          103
7.3      80       81     81       81
8.2 103         103 103          103       8.2 103         103 103          103
8.2      90       89     90       90
9.2 103         103 103          103
9.2    100      101     100      100
10.4    103      103     103      103
11.5    103      103     103      103
12.3    103      103     103      103

Which flame height has the fastest rate of heating?
Graphing All of the Data
Affect of Flame Height on Heating Curve
120

100

4" Flame Trial1
80
4" Flame Trial 2
Temperature (oC)

4" Flame Trial 3
60                                                           6" Flame Trial 1
6" Flame Trial 2
6" Flame Trial 3
40
5" Flame Trial 1
5" Flame Trial 2
5" Flame Trial 3
20

0
0   2    4        6                8   10    12   14
Time (min)
Graphing Mathematically Treated Data
Affect of Flame Height on Heating Curve
120

100

80
Temperature (oC)

60                                                                4" Flame
6" Flame
5" Flame
40

20

0
0   2     4         6                8   10       12   14
Time (min)
Tables Can Be Very Effective As Well

Even graphs can be made more succinct
if you are able to get the
right information out of your data

Flame Height   Heating Rate
(inches)       (oC/min)
4              9
5             14
6             18

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 views: 4 posted: 6/21/2012 language: pages: 14