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3
Use of the Educational Software
ISA'MATCH in the learning of
Mathematics in 8th grade
Uso del Software Educativo ISA’MATCH en el aprendizaje
de Matemática en 8avo de Básica
Angela Germania Váscones Rodríguez
*
Cecibell Eugenia Galarza Posligua*
José Miguel Arroba Castro*
Resumen
El presente artículo, tiene como objetivo principal integrar el
aprendizaje de la matemática con el software educativo
ISA’MATCH desarrollado en Haeduc. Para ello, se diseña una
sesión para el conocimiento del software educativo y seis sesiones
para el aprendizaje de la actividad, comprendida en la unidad de
álgebra y funciones de octavo año de educación general básica, que
incluyen contenidos, recursos, instrumentos y evaluaciones
necesarias para lograr resultados de aprendizaje óptimos. Para
complementar el uso del software educativo, se promueve el
aprendizaje de las metodologías activa y el modelo flipped
classroom, que facilita la interactividad de los alumnos con la
actividad de enseñanza - aprendizaje y mejora de éste. Para esta
propuesta fue necesario revisar la fundamentación teórica basada en
*
Master's Degree in Educational Technology and
Digital Competences, Teacher, Ministry of Education,
angela.vascones@educacion.gob.ec,
https://orcid.org/0000-0002-5558-7852
* Master's Degree in Educational Technology and
Digital Competences, Teacher, Ministry of Education,
cecibell.galarza@educacion.gob.ec,
https://orcid.org/0000-0003-2465-6525
* Master's Degree in Educational Technology and
Digital Competences, Teacher, Ministry of Education,
josearroba4@gmail.com, https://orcid.org/0000-0002-
7905-6888
Article
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el software educativo y la competencia matemática, para lograr
emplear adecuadamente las técnicas instruccionales y metodologías
que queremos combinar. Finalmente, la propuesta planteada ofrece
una herramienta de enseñanza que promueve el aprendizaje y la
motivación permitiendo al estudiante ser partícipe y responsable de
su proceso educativo y el docente sea el guía de este.
Palabras clave: Software educativo, Flipped Classroom, matemáticas,
metodología activa.
Abstract
The main objective of this article is to integrate the learning of
mathematics with the educational software ISA'MATCH developed
in Haeduc. For this purpose, a session is designed for the knowledge
of the educational software and six sessions for the learning of the
activity, included in the algebra and functions unit of the eighth year
of general basic education, which include contents, resources,
instruments and evaluations necessary to achieve optimal learning
results. To complement the use of educational software, the learning
of active methodologies and the flipped classroom model are
promoted, which facilitates the interactivity of students with the
teaching-learning activity and its improvement. For this proposal it
was necessary to review the theoretical foundation based on
educational software and mathematical competence, in order to
adequately employ the instructional techniques and methodologies
that we want to combine. Finally, the proposal offers a teaching tool
that promotes learning and motivation, allowing the student to
participate and be responsible for his educational process and the
teacher to guide him.
Keywords: Educational software, Flipped Classroom,mathematics,
active methodology.
Introduction
Nowadays, technology has become a great support in the teaching
and learning processes, becoming an integrating object of
knowledge, this support has been gradually evidenced in the
classrooms, reflecting a positive change in the present digital
natives.
It is important to emphasize that motivation in learning consists in
the use of didactic tools that facilitate the teacher to capture the
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student's attention, highlighting Montes, Escobar and Cadavid who
affirm:
The lack of understanding of mathematical language, is
presented due to the little reading that students do of
mathematical texts, which brings as a consequence the lack
of knowledge of the language, writing, notations, symbology
and other mathematical structures present in the books (2018,
p. 66).
However, the incorporation of Information and Communication
Technology (ICT) in teaching-learning methods has favored new
understandings and visions in modern schools without forgetting the
traditional pedagogical foundations. Therefore, this has provoked
the reflection of educational authorities, on educational programs
establishing a link between technology and the content of the
curricular program (Granda, Espinoza and Mayon, 2019).
Regarding the performance results and achievements of students in
Ecuador, the National Institute for Educational Evaluation (2018)
reveals that, mathematical competence corresponds to 29%,
compared to the reading level which corresponds to 49% and 43%
in science. These results reflect a high rate of students who fail and
the knowledge acquired during the school cycle has not been
sufficient or consequently assimilated during the process and the
next educational stage continues with learning complications until
reaching high school.
In sum, it is necessary to answer the premises of what for, what, how,
when to teach and what, how to evaluate that respond to the essential
elements of curricular planning that guarantees meaningful student
learning (Ministry of Education, 2017).
Pedagogical use of Educational Software in the classroom.
Currently, the use of educational software lies in the modernization
of educational tools with the objective of improving teaching and
learning processes, creating new didactic environments that allow
teachers to develop their classes in a creative, dynamic and
participative way. We could highlight Cruz, where he defines
Educational Software as:
A set of computer resources, specially designed to be used by means
of a computer, to facilitate the teaching-learning process of different
subjects. They are characterized by being highly interactive, based
on the use of multimedia resources, such as videos, sounds,
photographs, specialized dictionaries, explanations by experienced
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teachers, exercises and instructional games that support the
evaluation and diagnostic functions (2019, p.23).
On the other hand, educational software allows the acquisition and
assimilation of knowledge, allowing learning through a dynamic
environment that will contribute to the teaching-learning of students
at their own pace, while involving parents in the educational process
of their children von Feigenblatt (2021); Barros & Turpo, (2018);
(Bernal and Zaldívar, 2017). Similarly, for the development of
ISA'MATCH, the HaEduc tool has been chosen:
[...]. This application is intended for the development of
educational computer resources, using different types of
multimedia objects. Presentations, multimedia, educational
software collections and other applications can be developed
according to the user's creativity. It is a unique design of its
kind in Cuba for the management of desktop applications. It
has tools that allow two types of users: advanced users and
teachers, who can find editors that allow them to perform
different tasks in a very simple way. [...] (Tejera, 2018, para.
1).
The application is intended for the advancement of academic
computer elements, using different didactic resources. It has the
possibility of creating models, multimedia, academic program
collections and other applications according to the user's
imagination. Based on all these benefits, ISA'MATCH is developed
to strengthen teachers in the use of contents in a single tool under
their own planning.
The development of mathematical competence
"The teaching of mathematics is of great importance in today's
knowledge society, in which, there is a growing need to master from
basic to advanced topics in all training contexts" (Grisales, 2018,
p.200).
In another order of ideas, Suárez, Duardo and Rodríguez define
mathematical competence as:
Complex psychological configuration integrated by
mathematical knowledge, skills, procedures and
mathematical strategies, which together with metacognitive,
motivational components and personality qualities self-
regulate real and efficient performance in solving everyday
problems, understanding the world, and making decisions as
a constructive, committed and reflective citizen. (2020,
p.121)
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On the other hand, "successful achievement and learning in
mathematics remains a challenge worldwide, and great efforts are
made to advance improvement proposals, usually involving
teachers, in terms of their training, improvement or classroom
practice" (Cerda, Casas, & Ortega, 2017, p.1).
Currently, a variety of dynamic and collaborative learning scenarios
are offered where the construction of knowledge is an essential sub-
process in the development of competencies and skills of the
teaching-learning process that the student must possess in
mathematics (DGómez, 2019). In such a way, the student should
gradually achieve to develop his mathematical ability favoring
analysis, understanding, participation and sociability in the
environment. Each method applied by the teacher for the
achievement of these competencies becomes valid.
Therefore, in a digital society, teaching-learning should be framed in
ICT support to achieve the skills required at each educational level,
these should be duly complemented, improve the quality of
education, save time in processes and deepen a method of cultural
change (Gonzales, Trelles and Mora, 2017).
Materials and methods
The learning processes should be focused on the learner to improve
his or her school performance, "it appears then as a process of
construction of meaning. That is, the student is not limited to
acquiring knowledge, but constructs it" (Moreira, 2019, p.3). The
objective of this study is to propose the use of the ISA'MATCH
software using the active methodology with the flipped classroom
pedagogical model, as a response to the teacher's needs to use
technological and pedagogical didactic resources, achieving the
development of skills in students and lowering the high rate of failing
grades in mathematics.
On the other hand, flipped classroom focuses on inverting traditional
teaching methods in the classroom and includes collaborative
learning among peers, solving activities and problems while the
teacher guides the process. Cedeño and Vigueras, (2020). On the
other hand, with respect to learning processes, they should be
focused on active methodological strategies, which allow the learner
to prioritize the activity rather than the content. This means that there
are important changes in the behavior of teachers and students in
classroom work, incurring in the change of curricular planning,
activities and evaluations, promoting constructivist learning (Silva
and Maturana, 2017, p.45).
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Consequently, the use of the didactic tool ISA'MATCH developed
in HaEduc for the learning of mathematics corresponding to the
algebra and functions block of the eighth grade math book being the
following: Addition of whole numbers, Addition of whole numbers
of the same sign, Addition of whole numbers of different sign,
Properties of the addition of whole numbers, Addition of several
whole numbers (Exercises), directed to 22 students between the ages
of 11 and 12 years of the Educational Unit "Isabel La Católica" of
the city of Babahoyo - Ecuador, Resolution No. 0212/1874.
As for the proposed methodology, it provides the opportunity to
fulfill three phases for learning the activity that help to contextualize
the work environment: first, a session is designed for the knowledge
of the educational software, the second phase of knowledge
acquisition, corresponding to three sessions: I clarify, reinforce and
test myself, finally, the closing phase consolidation of knowledge:
session I prepare myself, I am evaluated and I demonstrate my
knowledge.
This process defines strategies with the students in each session,
establishes groupings to favor the learning of the proposed tasks and
evaluate the achievements obtained. The development of the
activities will be carried out with master classes contained in the
software so that the concepts are assimilated before each class, and
then reinforce what has been learned in the group plenary through
problems with individual and collective challenges that must be
achieved to achieve in students a critical, analytical and reflective
thinking, showing their results in the expository class.
First phase: Explanation of the use of the educational software
ISA'MATCH, the teacher motivates about the advantages of the new
learning method, exposes the concepts of educational software, ways
of working in the inverted classroom, the benefits and possible
obstacles that arise in the learning process shown in Table 1.
Table 1. Getting to know ISA'MATCH
Activity
Time: 40
minutes
Objectives: To orient students to the use of
the educational tool.
N° of students: 22
Grade: eighth grade
Contents: Visit of the windows
Activities:
Presentation and guide on the use of ISA'MATCH, explaining
installation, rules on the use of the contents of the unit to be
worked on and definition of times.
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Explanation of the use of the contents, activities and videos.
Students document in a portfolio the process and results of
their work as evidence of their process.
After reflecting on the use of ISA'MATCH, we proceed to the
clarification of doubts.
Delivery of the tool for installation on your personal
computer.
Performance
Indicators
Students know how to use the tool.
Resources
ISA'MATCH- projector, computer,
speakers.
Note: Table authored by the authors.
Home screens: These windows correspond to the main
environments of the software, where the menu of proposed topics is
shown, each one of them has navigation buttons to facilitate its use.
Second phase (knowledge acquisition): in session one the student
outside of class performs the strategy of the proposed activity for the
execution of the final project. This activity is designed to work with
the topics of addition of integers, with the help of the ISA'MATCH
software, which has the contents, videos and activities for a guided
learning and different from the traditional learning method on
blackboard and paper.
Next, students must activate their knowledge by reading the didactic
contents presented in ISA'MATCH before each class, according to
the content to be covered (the teacher organizes the extension of
time, according to difficulties that may arise). After observing the
contents, they must elaborate questionnaires with respect to the
doubts of the corresponding topic of the class. The planning of the
programmed session is presented in Table 2.
Table 2. Knowledge acquisition session
Activity
Knowing the integers.
Time: 40
minutes
Objectives: To guide students
in the application of whole
number addition exercises,
developing and stimulating
mathematical skills and
multiple intelligences.
Methodology: Active
and Flipped Classroom
model.
Grade: 8th grade
N° of students: 22
Contents:
Addition of whole numbers of the
same sign, Addition of whole numbers
of different signs, Properties of
addition of whole numbers, Addition
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of several whole numbers, Problem
solving.
Development
Session 1: Clarifying
In class, the teacher socializes and holds a
plenary session on the contents reviewed before
the session.
The teacher clarifies doubts that the students
have previously noted.
The teacher conducts with the students a
deepening of the topics studied and reinforces
the previous knowledge of the videos and
contents reviewed.
Performance
Indicators
Students make use of didactic
material prior to classroom
lessons.
Verification
Method
Review.
Material
resources
Desktop
computer.
Speakers.
Notebook and
pen.
Projector.
ISA'MATCH
Evaluation
criteria
Direct observation. Self-
assessment
Measurement
Evaluation
instruments
Heading
Note: Table of own authorship.
Afterwards, the teacher conducts session two in class to reinforce the
content reviewed by the students at home, followed by session three,
which consists of testing themselves, carrying out individual and
group activities, as shown in Table 4.
Table 4. Reinforcement sessions and proposed activities
Activity
My daily life problems in
integer addition.
Time: 40
minutes
each
session
Objectives: To solve integer
addition exercises, using
ISA'MATCH.
Methodology: Active
and Flipped
Classroom model.
Grade: 8th grade
N° of students: 22
Contents:
Problem solving.
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Development
Session 2: Reinforcement
The teacher mentions and exemplifies
mathematical problems related to everyday life.
Resources for class work are provided.
Individual activities with ISA'MATCH are
proposed to be solved in class (activities that do
not exceed the scheduled time and the teacher is
able to review the work are proposed).
The teacher observes and guides the students in
the problems that arise when solving the activity.
(always encouraging the use of ISA'MATCH for
reinforcement).
At the end of the work, review the results of the
activity performed.
Feedback of the class and clarification of general
doubts.
Session 3: I test myself
Form peer groups to solve practical problems of
daily life posed by the teacher and assign
resources.
Enter ISA'MATCH, and review the orders
described in the tool and resolve them on paper.
After analyzing the contents to be covered,
students should clarify their doubts and then
provide feedback on the contents.
Verify results by encouraging cooperative work.
Document your work and attach it to your
portfolio of evidence.
Performance
Indicators
Students make use of didactic
material prior to classroom
lessons.
Verification
Method
Review.
Material resources
Desktop
computer.
Speakers.
Notebook and
pen.
Camera.
Projector.
Cardboard
portfolio.
ISA'MATCH
Evaluation criteria
Direct observation. Self-
assessment
Measurement
Evaluation
instruments
Problem posing and solving.
Rubric, Portfolio of Evidence
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Note: Table of own authorship.
Closing Phase (consolidation of knowledge): at the end of the
development of the activities in Table 5, students should be
evaluated to determine if the competencies of the proposed topic
are achieved. To do this, each group must present the results of the
final work applied to daily life, using the resources offered by
ISA'MATCH as a guide. Each group must present an exercise and
show how to solve it to the rest of the group.
Table 5. Knowledge consolidation
Activity
What I learned with integers.
Time: 160
minutes
Objective: To measure the students'
performance in the development of the
proposed activity.
Methodology: Active
and Flipped Classroom
model.
Grade: eighth grade
N° of students: 22
Contents:
Problem solving.
Development
Session 4: I prepare myself
To measure the results of what has been learned in the
subject, it is proposed to the students:
Assignment of homework and organization of the material
to be exhibited.
Indications of the time your expository work should last.
Indications of what they are expected to present in their
final work.
Session 5: I am evaluated
(This session is developed in two times in order to comply with the
presentation of the work of all groups).
Statement of the problem posed.
Plenary of papers presented.
Session 6: Evidencing my knowledge
Delivery of the evaluation sheet.
Development of the test.
Performance Indicators
Master the skills required for the
application of integers in everyday
life.
Verification Method
Diagnostic test.
Material resources
Computer
Speakers
Notebook and pen
Camera
Projector.
Cardboard
portfolio.
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Evaluation criteria
Direct observation.
Self-evaluation.
Measurement
Registrations
Evaluation instruments
Heading
Portfolio of evidence.
Partial test
Note: Table of own authorship.
Results
After using the educational tool ISA'MATCH, designed and
elaborated based on the mathematical contents for the dynamic
understanding of the subject, the students have been evaluated since
"it is essential to apply mathematical thinking to problem solving, as
a fundamental way for the development of skills and decision
making in their professional life" (Navarro, 2017 p.1), we have
observed the positive development of the student and their learning
process, based on the rubric of attitude and performance, then each
student has evidenced their work by filing them in the student
portfolio prepared by them. In contrast, the evidence of the results in
ISA'MATCH, the design of the practical activities does not show the
final score of the correct answers, so it is not possible to verify a
statistic of lessons learned.
It is important to highlight that the use of the strategy proposed in
the innovation project allows the development of mathematical
competence, improving the quality of teaching. It is inferred that,
changing the traditional learning method for an innovative one to use
the tool in conjunction with the proposed methodologies, must be
accompanied by a well-designed planning, which implies that the
teacher innovates his practice in the classroom and the student
enhances his academic performance.
Discussion
Nowadays, "the way of learning has changed and, therefore, the way
of teaching. Knowledge is networked and teachers must be the ones
who accompany students in their learning process. Technology alone
does not guide" (Viñals and Cuenca, 2016, p.103), favoring the
technology-pedagogy relationship that has long been disconnected.
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It is convenient to highlight that for the application of the proposal
the students must have a computer to review the material at home
and the teacher must make use of the technology for the development
of the planning in the educational software.
In this sense, and taking advantage of the benefits of HAEduc, it is
recommended that, since it is easy to use, even for inexperienced
users, the teacher could update or design educational activities by
creating his own resources, regardless of the educational level or
field of knowledge. Therefore, in order to motivate students'
learning, the teacher can request the creation of explanatory videos
of the contents of the unit and add the most representative ones to
the tool.
Finally, it can be considered that the use of these advances favors the
student a new way of organizing, distributing, representing and
codifying reality, that is, it develops skills and abilities to build their
own knowledge.
References
Barros, C., & Turpo , O. (2018). Factors influencing the scientific
production of university professors: a systematic review.
Factores Que Influyen En La Producción Científica de Los
Docentes Universitarios: Una Revisión Sistemática., 11(22),
225–234. http://10.0.85.43/pensam.v11i21-
1.276%0Ahttps://ezproxy.uniandes.edu.co:8443/login?url=htt
p://search.ebscohost.com/login.aspx?direct=true&db=fua&A
N=141223533&lang=es&site=ehost-live
Bernal, M. A., & Zaldívar-Colado, A. (2017). Use of educational
software as a strategy to promote reading. Revista de
Investigación en Tecnologías de la Información, [S.l.], 5(9),
43-47.
https://www.riti.es/ojs2018/inicio/index.php/riti/article/view/
37
Cedeño-Escobar M. R, Vigueras-Moreno J. A. (2020). Aula
invertida una estrategia motivadora de enseñanza para
estudiantes de educación general Básica. Dominio de las
Ciencias, 6(3), 878-897.
https://dialnet.unirioja.es/servlet/articulo?codigo=7539749
Cruz, M. (2019). Methodological proposal for the use of educational
software as a didactic resource in research training. Revista
Sinergias educativas
January - March Vol. 7 - 1 - 2022
http://sinergiaseducativas.mx/index.php/revista/
13
ciencias pedagógicas e innovación, 7(2), 21-30.
https://doi.org/10.26423/rcpi.v7i2.288
DGómez, F. (2019). The development of mathematical
competencies in the Pedro Vicente Abadía Educational
Institution of Guacarí, Colombia. Universidad y Sociedad,
10(6), 162-171. http://rus.ucf.edu.cu/index.php/rus
Cerda, G., Pérez, C., Casas, J. and Ortega-Ruiz, R. (2017), Teaching
and Learning Mathematics: The need for a multidisciplinary
analysis. Psychology, Society, & Education, 9(1), 1-10.
https://www.researchgate.net/publication/316609724e9ff34e/
download
Gonzales, N. N., Trelles, C. A., & Mora, J. C. (2017). Teaching
management of information and communication technologies.
Cuenca, Ecuador. INNOVA Research Journal, 2(4), 61-72.
https://doi.org/10.33890/innova.v2.n4.2017.153.
Granda, L. Y., Espinoza, E. E., & Mayon, S. E . (2019). ICTs as
didactic tools in the teaching-learning process. Conrado,
15(66), 104-110.
http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1990-
86442019000100104&lng=es&tlng=es.
Grisales, A. M. (2018). Use of ICT resources in mathematics
education: challenges and perspectives. Entramado, 14(2),
198-214. https://doi.org/10.18041/1900-
3803/entramado.2.4751
National Institute for Educational Evaluation. (2018). PISA for
Development results. Retrieved from
http://www.evaluacion.gob.ec/evaluaciones/pisa-
documentacion/
Ministry of Education. (2017). Instructivo para Planificaciones
Curriculares para el Sistema Nacional de Educación.
https://educacion.gob.ec/wp-
content/uploads/downloads/2017/06/Instructivo_planificacio
nes_curriculares-FEB2017.pdf
Montes, J., Escobar, R. and Cadavid, G. (2018).Use of
Technological Tools in the Development of a Mathematics 1
course at the Technological University of Pereira. Entre
Ciencia e Ingeniería, 12(23), 66-71.
http://www.scielo.org.co/pdf/ecei/v12n23/1909-8367-ecei-
12-23-00066.pdf
Moreira, P. (2019). Meaningful learning and its role in the social and
cognitive development of adolescents. Rehuso, 4(2), 1-12.
https://dialnet.unirioja.es/servlet/articulo?codigo=7047160
Navarro, L. (2017). Mathematical thinking: a necessary tool in the
initial training of mathematics teachers. VARONA, (esp.), 1-7.
https://www.redalyc.org/articulo.oa?id=360657468016
Sinergias educativas
January - March Vol. 7 - 1 - 2022
http://sinergiaseducativas.mx/index.php/revista/
14
Suárez, J., Duardo Monteagudo, C., and Rodríguez Marín, R .
(2020). The development of mathematical competence
through problems with applications of functions. Chakiñan,
Revista De Ciencias Sociales Y Humanidades, (12), 118-134.
https://doi.org/10.37135/chk.002.12.08
Silva, J. , & Maturana, D. (2017) . A model proposal to introduce
active methodologies in higher education. Innovación
educativa (Mexico, DF), 17(73), 117-131.
http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=
S1665-26732017000100117&lng=es&tlng=es.
Tejera, H. (November 30, 2018). HAEduc.
https://cbithumbertotejera1.wordpress.com/haeduc/
Viñals, A., and Cuenca, J., (2016). The role of the teacher in the
digital era. Revista Interuniversitaria de Formación del
Profesorado, 30 (2), 103-114.
https://www.redalyc.org/articulo.oa?id=27447325008
von Feigenblatt, O. F. (2021). Human Trafficking in Thailand: The
Complex Contextual Factors. Journal of Asia Pacific Studies
(2021) Volume, 6, 137-146.