<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Application of Learning Analytics techniques on blended learning environments for university students</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Sheila Lucero Sánchez López</string-name>
          <email>1sheila.lucero@det.uvigo.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Rebeca P. Díaz Redondo</string-name>
          <email>2rebeca@det.uvigo.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ana Fernández Vilas</string-name>
          <email>3avilas@det.uvigo.es</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>School of Telecommunications Engineering. I&amp;C Lab. AtlantTIC Research Center. University of Vigo.</institution>
          <addr-line>36310 Vigo.</addr-line>
          <country country="ES">Spain</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2019</year>
      </pub-date>
      <fpage>9</fpage>
      <lpage>21</lpage>
      <abstract>
        <p>The educational process is constantly changing. On the one hand, traditional educational methods have been modified and, on the other hand, the model of educational transmission has also changed. According to different authors, technological resources, specifically the eLearning platforms, and social interaction are responsible for these changes. Based on these approaches, this article applies Learning Analytics techniques with the aim of analyzing social interaction in blended-learning environments. For this, an exploratory analysis will be carried out in the messages published in the forums with the objective of qualitatively analyzing the students' interaction with the educational platform.</p>
      </abstract>
      <kwd-group>
        <kwd>Learning Analytics</kwd>
        <kwd>e-learning</kwd>
        <kwd>Forums</kwd>
        <kwd>Learning Acquisition</kwd>
        <kwd>Educational Data Mining</kwd>
        <kwd>social interaction</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>Introduction</title>
      <p>integrate a set of tools for the online teaching-learning process, with the aim of
allowing the creation and management of teaching and learning spaces on the Internet,
where teachers and the students can interact during their training process. The boom
of these platforms has been so great that they are currently used in different
educational levels and in different parts of the world. In fact, according to the combination
of technological resources with the degree of presence that the student has while
learning, we can find three widely accepted teaching modalities: traditional modality,
e-learning and blended-learning.</p>
      <p>
        The traditional modality is when the student receives the knowledge in its entirety
inside the classroom, in the same space-time as the teacher without the presence of
technological resources provided by the (ICTs). The e-learning modality is also called
online education modality. In this, the teaching is taught entirely remotely over the
Internet, without the need for students to interact with the platform at the same time or
in the same geographical location as the teacher. This allows the student to advance at
his own pace, making his learning process more flexible and favoring his autonomy
[
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. The modality blended-learning or mixed education, arises when the lessons in the
classroom complement each other with the educational platform. Fusing this way, two
pedagogical approaches that combine the effectiveness and opportunities of
socialization of the class with the technological improvements of online learning [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ].
      </p>
      <p>These platforms have the capacity to store an innumerable amount of data from the
interaction of users (students and teachers) with them and through them. Despite the
success and acceptance that these platforms are having, these do not have per se any
tool to facilitate the interpretation or analysis of this data. However, these data have
aroused the interest of many researchers, thus emerging two specialized fields of
study: Learning Analytics (LA) and Educational Data Mining (EDM).</p>
      <p>
        According to the First International Conference on Learning and Knowledge
Analysis (LAK 2011) [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], LA "is the measurement, collection, analysis and reporting of
data about learners and their contexts, for purposes of understanding and optimizing
learning and the environments in which it occurs.”. On the other hand, EDM is
defined as "the development, research and application of computerized methods to
detect patterns in large collections of educational data that would otherwise be difficult
or impossible to analyze due to the huge volume of existing data" [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
      </p>
      <p>
        Both areas share different challenges. However, this work has been developed
under the proposal of LA, based on the approach proposed by [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] "Learning Analytics
refers to the interpretation of a wide range of data generated and collected on behalf
of the student to evaluate their academic progress, predict their future performance,
and locate potential problems. The data is collected from explicit student actions, such
as performing evaluable exercises or tests, and from unspoken actions, including
social interactions, extracurricular activities, publications in a discussion forum and
other activities not directly evaluated as part of the educational progress of the
student. The goal of Learning Analytics is to support teachers and schools in the process
of adapting their learning opportunities to the level of need and ability of their
students in real time (or with a fairly tight margin)".
      </p>
      <p>
        It is also necessary to emphasize that not only the teaching modality has changed,
also the model of transmission of knowledge has been transformed. According to
[
        <xref ref-type="bibr" rid="ref10">10</xref>
        ], two types can be distinguished: on the one hand there is the model where the
teacher plays the central role as wise on stage, called "sage on the stage" and, on the
other hand, there is the model where the teacher and the student jointly create the
learning environment, called "guide on the side". In this case the role of the teacher is
to be a side guide.
      </p>
      <p>
        Several authors support the idea that interpersonal interaction provide the
advantages of the second model. This type of interaction is generated when students
react to the content and share concerns, they teach each other learning in a tangible
way when they express with words (through publications on the platform) their own
understanding and assumptions, which allows them to appropriate new skills and
ideas, at all times being focused and deepened by the lateral guide, without it
hindering the development and learning experience of the students [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. Likewise, in the
literature we can find numerous studies that prove that a greater participation in terms
of quality and quantity can increase learning. Otherwise, by controlling the design
elements of technological resources and the execution of the course, participation and
learning can be increased [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ], [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ], [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>
        Starting from the premises that e-Learning platforms and interpersonal interaction
(or also called, social interaction) are of great importance in the new changes that are
arising in the educational process. In this paper we will study the application of LA
techniques in blended-learning environments focused on university studies. To this
end, a methodology will be presented that allows qualitatively analyzing the
interpersonal interaction of students in the e-Learning platform. Our approach tries to take
advantage of the information exchange in the online forums to discover new
knowledge about the students’ way of learning or behave. In this paper, our work
done in [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] is broadened by analyzing social interaction from a qualitative
perspective, since in the work cited, social interaction is only approached from a quantitative
perspective.
      </p>
      <p>To do this, the data extracted from the official platform of the University of Vigo
belonging to a programming course along three different academic years of
Telecommunications Engineering will be used.</p>
      <p>This document is structured as follows. The following section (section 2) provides
a description of the data set and the methodology. Subsequently, in section 3 we will
analyze the students qualitatively, analyzing their messages and publications in the
forums of the e-Learning platform. Finally, in section 4 the results will be analyzed.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Description of Dataset and Methodology</title>
      <p>To perform our experiments, we use data from a course related to the programming
skills of the third year course of a Bachelor Degree on Telecommunication
Engineering. This is a blended course of fourteen weeks between September and January. The
dataset was gathered from the official e-Learning platform, Moodle-based, of the
university where the subject was taught.</p>
      <p>The assessment mechanism of this course is based on three mandatory assignments
distributed along the course (from the fourth to the last week) as Fig. 1 shows. The
forum is accessible to all students and used to debate about different aspects related to
the course (content or administrative issues), answer questions, solve doubts, etc.
However, it should be noticed that it does not represent any mandatory activity. The
required assignments are divided in two types:
• Laboratory: To determine if the student has acquired all the knowledge and skills
corresponding to the laboratory practices (3 practices).
• Applied: To determine if the student knows how to apply the knowledge of the
course to solve problems (2 exams).
The Moodle platform stores in its database not only all the information related with
the courses (course contents, personal data of students and professors, students’
grades, etc.), but also all the information about the students’ interaction with the
platform. In fact, Moodle distinguishes between different types of interactions, which are
classified in ten different modules (Assignment, Blog, Choice, Course, Forum, Notes,
Resource, Upload, User, and Quiz) as Table 1 shows.
For our analysis, we gathered data (73,849 interactions) from three academic years.</p>
      <p>We analyze data of 435 students organized from 2014 to 2017, as shown in Table 2.
Academic Year
2014/2015
2015/2016
2016/2017</p>
      <p>Total
As mentioned above, we will analyze two types of interaction: interaction with
content and social interaction. Initially, we have divided the events into two groups: (i)
actions related with some contents or class notes and (ii) actions related to
interpersonal activities. The objective is to find the group of activities that have a higher
relation with one of both interaction types.</p>
      <p>We consider the following classification: the modules Assignment, Course, Notes,
Resource, Upload, and Quiz are related to content. Blog, Choice and Forum are
related to interpersonal interaction. Use is outside of both classifications, because it does
not provide information related to this.</p>
      <p>Modules Blog, Choice and Forum are considered as interpersonal participation
because the students can show their own ideas in module Blog. On module Choice they
can choose and propose surveys and discussions, and finally, in module Forum,
students can participate in a more active way.</p>
      <p>Our methodology is divided into three stages. The qualitative analysis begins with
data preprocessing, continues with the classification of the messages in three groups
and ends with an exploratory analysis of the content of the messages.
3</p>
    </sec>
    <sec id="sec-3">
      <title>Qualitative analysis</title>
      <p>As mentioned earlier, this analysis is divided into three stages: the first one
corresponds to the data preprocessing; the second one is a classification of the messages in
three categories (content, code and other); and finally the exploratory analysis of the
content of these categories.
3.1</p>
      <sec id="sec-3-1">
        <title>Data Preprocessing</title>
        <p>It is necessary to prepare and transform the gathered information to classify the
messages. Initially, a corpus of specific content has been created for the experiment,
extracting the main words (topic words) from 12 pdf files: teaching material (4 pdf
files), educational resources (3 pdf files), notes (3 pdf files), slides (2 power point
files), three practices (3 files) and references in the presentations of the class (2 pdf
files). All information is available to any student enrolled in this subject and with
access to the official e-Learning platform of the university. From these documents, we
have obtained a total of 15,704 words. This set is latter reduced to a corpus of 587
words, after removing stopwords, carrying out a lemmatization and extracting the
topic words. This corpus will be called “Content Corpus”.</p>
        <p>As it was previously commented, the content of the subject is related to computing,
especially to two programming technologies: Java and HTML. For this reason, the
use of programming codes is very frequent. Therefore, we use a second corpus that
will be called “Code Corpus”, created by RANKS NL that contains the top words of
all programming languages.</p>
        <p>
          RANKS NL [
          <xref ref-type="bibr" rid="ref16">16</xref>
          ] is a keyword analyzer tool for URLs, websites, texts and
documents to improve search engine optimization and other purposes. It has available a
collection of stopwords’ lists in more than 40 languages and the list of reserved words
of Perl, Mysql, Javascript, C, C++ and HTML. In the same way, the stopwords raised
by RANKS NL will be removed of all the messages.
        </p>
        <p>As a summary, the two corpus that we will use to classify the messages are:
─ Content Corpus: created by the extraction of the main words (topic words) of the
teaching material, educational resources, notes, slides, practices and references
available in the e-Learning platform. It is composed of 587 words.
─ Code Corpus: this corpus will serve to classify messages that contain programming
codes and it is based on the corpus armed by RANKS NL. It is composed of 2,500
words.
3.2</p>
      </sec>
      <sec id="sec-3-2">
        <title>Classification. The next step will be classifying the exchanged messages in the forums. Naive Bayes classifier and the two corpus (Code and Content) will be used for this task. By Bayes theorem, the probability can be defined as:</title>
        <p>( | 1 =  ,  2 =  ,   = ⋯ ) =
 ( ) ( 1 =  ,  2 =  ,   = ⋯ )
 ( 1 =  ,  2 =  ,   = ⋯ )
(1)
Where  ( ) is the probability of belonging to the specific corpus (Code or Content);
  is the identifier of word;  represents if it belongs to the corpus; and  if it does
not belong to it.</p>
        <p>Our interest is the relative probabilities of the messages being a code message or
content message. In other words, the exact value of the probability is not important
because the classification will be assigned according to the highest percentage of
belonging to any of the corpus. Therefore, we can factor out any terms that are
constant, namely the denominator of the above equation is a constant because it depends
on the total number of messages (from both types – content and code -). For this
reason, the numerator of equation (1) can then be written as:
 ( ) (| 1 =  ,  2 =  ,   = ⋯ ) =  ( ) ( 1 =  | ) ( 2 =  | ) (  = ⋯ ) (2)</p>
        <p>Each message will follow the same process. First, divide each message word by
word. Second, stopwords are removed and lemmatization is executed. Third, the
messages are classified using the Naïve Bayes classifier if the message has 33%
membership in the code or content corpus. This percentage is recommended by RANKS NL,
creator of the code corpus. This percentage is recommended when using this classifier
for detecting spam in emails. Finally, we obtain three classifications.
1. Code messages: messages that 33% of its content belongs to the code corpus.
2. Content messages: respecting the same percentage, these are messages that 33% of
its content belongs to the message corpus.
3. Other messages: the rest of messages that do not belong to any of the two previous
classifications.</p>
        <p>The procedure considers that the same message can contain words that belong to the
two corpus. As shown in Fig. 2, first, it calculates the probability of each word of
belonging to the code corpus and get the value of the probability. Then, it calculates
the belonging to the content corpus, word by word, until exceeding the percentage of
belonging to the code corpus or finishing by analyzing all the words of the message.
Finally, the classification with the highest percentage is assigned, as long as it exceeds
33%.
To check the classification, an expert in the programming area reviewed each
message to classify them manually in the three identified groups, obtaining that only
7.2% of messages correspond to another category different from the one assigned by
the Naïve Bayes classifier. With this information, we have calculated other interesting
measures of accuracy like precision, recall and F score, summarized in Table 3.</p>
        <p>Code
Content
Other
As previously mentioned, we have decided to use the threshold of 33% to decide if a
message would belong to the Content category, keeping the recommendation by
RANKS. This value supported good result. However, we decided to perform some
tests changing this threshold. After doing an exhaustive work, we detected that our
results were optimized using a higher threshold of 52%: our error decreased to 5.7%
and the total recall increased from 92.8% to 94.3%. This encouraged us to check what
happened if the threshold of the Code category was also altered. After the same
analysis, we optimized our results increasing this threshold to 35%.</p>
        <p>Finally, Table 4 summarizes the distribution of messages per academic year:
content messages are clearly the most frequently exchanges and code messages the less
frequent. Since the percentages are quite similar in the three academic years, we have
decided to focus the analysis in a single data set formed by the information of the
three academic years (2014-15, 2015-16, and 2016-17).
It is important to emphasize that we will analyze the content of the three
classifications by performing an exploratory analysis. We will search the most frequently used
words in the previously classified messages. This will allow us to know which are the
top words and if there is a relationship between the classifications. Moreover, the next
step is to plot networks of these co-occurring words, so these relationships are clearly
displayed, as Fig. 3 shows.
Considering that n represents the co-ocurrence of the words in Fig. 3, it was found
that several words are indistinctly used in the Code category and in the Content
category, such as entity, permissions, firewalls, browser, or route. Besides, there are
words that appear in the Other category and in the Content category, such as exam,
results, deliver, attachment or correction. Finally, there are words that appear in the
three corpus: php, tomcat, query, server, etc. We can see that the words of the Other
category are referring to the course administration, therefore this classification will be
named as such.</p>
        <p>Additionally, Fig. 4 shows the distribution of the messages of each category along
the academic term, showing the temporal evolution of the exchanges messages.
As Fig. 4 shows, we have 3 peaks (blue circles) of code messages, the first
corresponds to the delivery of the first practice, the second to the revision of the second
practice and the third to the delivery of the third practice. We also have 2 peaks
(orange circles) in content messages corresponding to the session prior to the exams.
Regarding the messages of the course administration, there is no pattern depending on
the academic organization of the course.</p>
        <p>To finish our exploratory analysis, it is important to know who initiates the posts: a
teacher or a student. It was obtained that 71% of code conversations, 63% of content
conversations and 55% of information conversations are started by students in each
group.</p>
        <p>Knowing that the student starts mainly the posts, the next point would be to know
which messages respond most frequently, those sent by the teacher or by the other
students. For this reason, we have calculated the percentage of the student's response
to conversations initiated by one of their classmates, knowing that 89% of the
messages sent by another student is answered. Only 11% is initially answered by the
teacher.</p>
        <p>
          Additionally, we have analyzed the themes and topics of the exchanged messages
with a program called DepPattern [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. It is a linguistic package providing a grammar
compiler, PoS taggers, and dependency based parsers for several languages including
Spanish and Galician. This is a very important feature, because the messages in the
forum are written in two languages (Spanish and Galician). Fig. 5 shows an example
of the results obtained by the software. The list of infinitive verbs, punctuation marks
and nouns of the messages were obtained by DepPattern.
Therefore, when interpreting the results we have obtained the following topics:
1. Questions mainly about delivery schedules and tests’ dates and a reminder of
instructions.
2. Recommendations of alternative content, specific questions and questions about
the relevance of the exercises.
3. Ask about exam dates and deliveries, make assumptions and the questions are
more general.
4. Examples’ requests, references to class slides, web links, feedback and answers to
questions.
5. Ask giving answer options, ask several questions in the same message, give
examples and alternatives, attach extra resources, the messages are longer.
4
        </p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Discussion and conclusions</title>
      <p>
        As a brief summary, two corpus were used in the analysis. The first (content corpus)
was created specifically with the academic content of the course, and the second
(code corpus) was taken from the one created by RANKS NL. Applying the Naïve
Bayes classifier and these two corpus, we have obtained three classes or categories:
code, content and course administration. The first two are composed of messages
with a high percentage of words related to code and course content, respectively.
Those messages which are not classified in these two categories go directly to the
third one, whose name was decided after checking that all the messages included
reference to course administration (questions and/or information about the exams,
revision dates, etc.). We chose this classifier because its structure is fixed and does
not depend on the data, it follows a generative or discriminative criterion. Like the
other Bayesian classifiers, the obtaining of the parameters is based on the maximum
likelihood or a posteriori maximum estimations [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ]. In addition, this classifier has
shown good results in the classification of texts [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ].
      </p>
      <p>The analysis of the messages can give feedback from the students to the teachers,
remarking those topics that are considered more interesting or those in which doubts
usually arise. Having a direct feedback from the student is important to be able to take
more concrete actions and improve the academic course, for example, reviewing
certain concepts, solving concerns, repeating dates or instructions and, consequently,
supporting the student in his acquisition of knowledge from a less formal environment
(forums) than the classroom. Forums can encourage shy or absent students to interact
with other students and, in the same way, they can encourage the more participatory
students continue to reinforce their interaction. The proposed methodology can bring
improvements inside and outside the classroom. It marks an important guide in the
educational process, by facilitating the content analysis of the messages in the forum,
identifying the main topics of discussion, the topics that more generate doubts, the
answers and the recommendations that are given between students. This allows to
analyze valuable data of student behavior, with which learning models and learning
analysis could be applied to improve the quality of education and the participation of
students.</p>
      <p>As a future line, on the one hand, it would be interesting to integrate the
classification of students to analyze the content of the messages for each profile proposed by
the classification and, on the other hand, to use these messages to try to profile the
student who sent them. This methodology could be an initial step to integrate a
content recommender system into the eLearning platform.</p>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgments</title>
      <p>This work is funded by the European Regional Development Fund (ERDF) and the
Galician Regional Government under the agreement of funding the Atlantic Research
Center for Information and Communication Technologies (AtlantTIC); the Spanish
Ministry of Economy and Competitiveness under the National Science Program
(TEC2014-54335-C4-3-R, TEC2017-84197-C4-2-R).</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <given-names>Parlamento</given-names>
            <surname>Europeo</surname>
          </string-name>
          ,
          <article-title>"</article-title>
          <source>Decisión nº 2318/2003/CE del Parlamento Europeo y del Consejo</source>
          de 5 de diciembre de
          <year>2003</year>
          <article-title>por la que se adopta un programa plurianual (2004-2006) para la integración efectiva de las tecnologías de la información y la comunicación (TIC) en eLearning,"</article-title>
          Diario Oficial de la Unión Europea, Vols. L-
          <volume>345</volume>
          , no.
          <issue>2318</issue>
          , pp.
          <fpage>9</fpage>
          -
          <lpage>16</lpage>
          ,
          <year>2003</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2. U.S. Department of Education,
          <article-title>"Getting America's students ready for the 21st Century: Meeting the technology literacy challenge</article-title>
          .,
          <source>" National Education Technology Plan</source>
          , p.
          <fpage>3</fpage>
          ,
          <year>1996</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Guttman</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <article-title>"Education in and for the Information Society," United Nations Educational, Scientific and Cultural Organization (UNESCO</article-title>
          ), Paris,
          <year>2003</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Fernández-Pampillón Cesteros</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <article-title>"Las plataformas e-learning para la enseñanza y el aprendizaje universitario en Internet.," in Las plataformas de aprendizaje. Del mito a la realidad</article-title>
          ., Madrid, Biblioteca Nueva,
          <year>2009</year>
          , pp. pp.
          <fpage>45</fpage>
          -
          <lpage>73</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>Cabero</surname>
            ,
            <given-names>J.</given-names>
          </string-name>
          ,
          <article-title>"Bases pedagógicas del e-learning,"</article-title>
          <source>Revista de Universidad y Sociedad del Conocimiento</source>
          , vol.
          <volume>3</volume>
          , no.
          <issue>1</issue>
          ,
          <year>2006</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Norberg</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Dziuban C. D.</surname>
          </string-name>
          , and
          <string-name>
            <surname>Moskal</surname>
            ,
            <given-names>P. D.</given-names>
          </string-name>
          ,
          <article-title>"A time‐based blended learning model," On the Horizon</article-title>
          , vol.
          <volume>19</volume>
          , no.
          <issue>3</issue>
          , pp.
          <fpage>2017</fpage>
          -
          <lpage>216</lpage>
          ,
          <year>2011</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>LAK</surname>
          </string-name>
          ,
          <article-title>"Call for Papers of the 1st International Conference on Learning Analytics &amp; Knowledge (LAK</article-title>
          <year>2011</year>
          )
          <article-title>" in LAK, Banff</article-title>
          , Alberta,
          <year>2011</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Romero</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          and
          <string-name>
            <surname>Ventura</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <article-title>"Data mining in education," Wiley Interdisciplinary Reviews: Data Mining and Knowledge Discovery</article-title>
          , no.
          <issue>3</issue>
          , pp.
          <fpage>12</fpage>
          -
          <lpage>27</lpage>
          , Enero,
          <year>2013</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Johnson</surname>
          </string-name>
          , L. ,
          <string-name>
            <surname>Conery</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          and
          <string-name>
            <surname>Krueger</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          ,
          <source>The NMC Horizon Project: 2011 K-12 Edition</source>
          , Austin, Texas: The New Media Consortium,
          <year>2011</year>
          , pp.
          <fpage>26</fpage>
          -
          <lpage>29</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>Bento</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Brownstein</surname>
            ,
            <given-names>B. and C.</given-names>
          </string-name>
          &amp;.
          <string-name>
            <surname>Schuster</surname>
            ,
            <given-names>Z.</given-names>
          </string-name>
          ,
          <article-title>"Fostering Online Student Participation,"</article-title>
          <source>Journal of College Teaching and Learning</source>
          , vol.
          <volume>2</volume>
          , no.
          <issue>7</issue>
          , pp.
          <fpage>31</fpage>
          -
          <lpage>37</lpage>
          ,
          <year>2005</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Collison</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Tinker</surname>
            ,
            <given-names>R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Elbaum</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          and
          <string-name>
            <surname>Haavind</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <source>Facilitating Online Learning: Effective Strategies for Moderators</source>
          , Madison: Atwood Publishing,
          <year>2000</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Harasim</surname>
            ,
            <given-names>L. M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Hiltz</surname>
            ,
            <given-names>S. R.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Teles</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          and
          <string-name>
            <surname>Turoff</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <article-title>Learning Networks: A Field Guide to Teaching and Learning On-</article-title>
          <string-name>
            <surname>Line</surname>
          </string-name>
          , Cambridge: The MIT Press,
          <year>1995</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Kemery</surname>
            ,
            <given-names>E.</given-names>
          </string-name>
          ,
          <article-title>"Developing On-line Collaboration," in Web-Based Learning and Teaching Technologies: Opportunities and Challenges</article-title>
          , Baltimore, Idea Group Publishing,
          <year>2000</year>
          , pp.
          <fpage>227</fpage>
          -
          <lpage>245</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          14.
          <string-name>
            <surname>Adrianto</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Yesmaya</surname>
            ,
            <given-names>V.</given-names>
          </string-name>
          and
          <string-name>
            <surname>Chand</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <article-title>"Increasing Learning Frequency through Education Based Game,"</article-title>
          <source>Journal of Computer Science</source>
          , vol.
          <volume>11</volume>
          , no.
          <issue>3</issue>
          , pp.
          <fpage>567</fpage>
          -
          <lpage>572</lpage>
          ,
          <year>2015</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <given-names>Sánchez</given-names>
            <surname>López</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S. L.</given-names>
            ,
            <surname>Díaz</surname>
          </string-name>
          <string-name>
            <surname>Redondo</surname>
          </string-name>
          , R. P. y Fernández Vilas,
          <string-name>
            <surname>A.</surname>
          </string-name>
          «
          <article-title>Predicting students' grade based on students behavior,» International Journal of Engineering Education (IJEE).</article-title>
          , vol.
          <volume>34</volume>
          , nº 3, p.
          <fpage>940</fpage>
          -
          <lpage>952</lpage>
          ,
          <year>2018</year>
          ..
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16.
          <string-name>
            <surname>Doyle</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <article-title>"Ranks.nl," Ranks, [Online]</article-title>
          . Available: https://www.ranks.
          <source>nl/about. [Accessed 11</source>
          <year>2017</year>
          ].
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          17.
          <string-name>
            <surname>Gamallo</surname>
            <given-names>Otero</given-names>
          </string-name>
          ,
          <string-name>
            <given-names>P.</given-names>
            and
            <surname>Gonzalez</surname>
          </string-name>
          ,
          <string-name>
            <surname>I.</surname>
          </string-name>
          ,
          <article-title>"DepPattern: a Multilingual Dependency Parser,"</article-title>
          <source>in The 10th International Conference on the Computational Processing of Portuguese</source>
          , Coimbra, Portugal,
          <year>2012</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          18.
          <string-name>
            <surname>Santafé</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Lozano</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Larrañaga</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          , «Aprendizaje discriminativo de clasificadores Bayesianos,» Inteligencia Artificial, Revista Iberoamericana de Inteligencia Artificial, nº
          <volume>29</volume>
          , pp.
          <fpage>39</fpage>
          -
          <lpage>47</lpage>
          ,
          <year>2006</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          19.
          <string-name>
            <surname>Palazuelos</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>García-Saiz D. y Zorrila</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          «
          <article-title>Social Network Analysis and Data Mining: An Application to the E-learning Context,»</article-title>
          <source>Proceedings of the 5th International Conference on Computational Collective Intelligence</source>
          , pp.
          <fpage>651</fpage>
          -
          <lpage>660</lpage>
          ,
          <year>2013</year>
          .
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>