cess in successive approximations based on the mea-
surement, visualization, correction of the necessary
parameters and, if necessary, repetition of the mea-
surement, is what leads to the correct realization of
the experiment. On the one hand, the processing of
the data is going to produce a totally satisfactory re-
sults. On the other hand, and undoubtedly also, it will
allow the students to actually acquire the associated
competences in a natural way.
It is interesting to compare the procedure with the
action of only producing a table containing just the
necessary information to do some calculations and to
obtain the requested values. Clearly, such a table con-
tributes nothing to the competences of the student. If
anything, it creates boredom and apathy about the lab
sessions. Apathy that increases as the students take
part in more and more lab sessions, which in turn
causes the competences associated with the experi-
ments not to be acquired and, also, causes “going to
the laboratory” to be just an easy and necessary for-
mality: it is enough to show up and collect the data in
order to pass the subject; taking data turns the process
into a mere data collection process, without any other
consideration or reflection on their quality, meaning
or usefulness.
Data processing, is traditionally carried out in the
laboratory. In fact, in the first year of the Physics de-
gree in our university, in the subject called Experi-
mental Techniques I, the students must perform the
data processing in the same session in which the data
are collected; and the session report has to be sub-
mitted before leaving the lab. Data processing (2) is
very important, since it leads to the cognitive develop-
ment of a large number of concepts (error estimation,
propagation of errors, importance of measuring some
variables instead of others, possible design of experi-
ments ...) and it helps acquire or refine a large number
of skills (differentiation, integration, qualitative cal-
culations, approximations, graphical representations
...). These competences are very useful not only for
lab sessions, but also for the rest of the subjects in the
degree. The data processing stage consists, in turn,
of two sub-stages; namely: 1) the knowledge and the
use of the tools necessary to carry out the treatment,
and 2) the treatment of the actual data themselves.
One must know whether a linear regression must be
made and how it is done, and how the results of the
fitting must be presented: with its errors, which have
been propagated or not, with their significant figures;
making the necessary tables, with the variables indi-
cated, accompanied by their units; constructing the
appropriate graphical representations, with the indi-
cated variables, accompanied by their errors, in the
appropriate scale and with the indicated and adequate
precision of the experiment. It is necessary to know
how the final results are interpreted: if the experiment
makes sense, if the variable measured behaves as ex-
pected; if the statistics is adequate; if it is necessary to
repeat some measurement or series of measurements,
and why; if there are several trends, what happens if
some points or series of points are removed, how the
behavior changes and why, whether or not to remove
them; what would happen if it were measured in an-
other interval, or in other measurement conditions (if
possible).
The first sub-stage, 3.1, consists itself of another
two levels. First, the knowledge of how to carry out
the task: how a linear regression is done; how the
propagated errors are calculated; how and why the
significant figures are assigned and what they mean;
how the representation window, the appropriate scale
and precision are chosen; which is the dependent vari-
able and which is independent. Second, the action
level: calculations have to be done to obtain the inter-
cept and slope, and their corresponding errors, results
have to be truncated and graphical representations fol-
lowing the criteria dictated by the knowledge of the
first level have to be performed. Nowadays the sec-
ond level has typically an automatic character (and
our university is no exception), in the sense that al-
most all calculations are made in a fast, reproducible
and reliable way using computers and more or less
sophisticated computer packages. It is important to
do this in this way because, among other things, the
students are being trained for the real world in which
people do not work with graph-paper to make graphi-
cal representations, nor are the calculations or regres-
sions done by hand.
Obviously this second sub-stage has much to do
not only with the data treatment itself, but with their
visualization, analysis and interpretation, or, in other
words, with the (previous) data collection stage of the
session. As mentioned above, in the second sub-stage,
in the data collection stage, the data obtained are in-
terpreted and decisions about the experiment itself are
made: whether to continue, to stop, to repeat, or to
consider other venues such as other measuring inter-
val... In short, the experiment is being completed, al-
ternatives are being considered, others are being dis-
carded and, some others, simulated. All this allows
students not only to actually learn in-situ, with the
possibility of rectifying, but to do it absolutely mo-
tivated, since they realize that the experiment devel-
ops, either positively (because one gets what was ex-
pected) or negatively (when one knowns what and
why something does not work), all of which allow
competences to be acquired more naturally and eas-
ily.
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