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PLATA: Design of an Online Platform for Chemistry Undergraduate
Fully Automated Assignments
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Miguel Reina,* Eduardo Gabriel Guzmán-López,* César Guzmán-López,
Carlos Hernández-Garciadiego, María de los Á ngeles Olvera-León, Mario Alfredo Garcia-Carrillo,
Marco Antonio Tafoya-Rodríguez, Victor Manuel Ugalde-Saldívar, Itzel Guerrero-Ríos, Laura Gasque,
Jorge M. del Campo, Daniela Franco-Bodek, Rolando Bernal-Pérez, Milton Medeiros,
Armando Marín-Becerra, Héctor García-Ortega, Jesús Gracia-Mora, and Antonio Reina*
Cite This: J. Chem. Educ. 2024, 101, 1024−1035
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sı Supporting Information
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ABSTRACT: In the Digital Era, the development of new
educational instruments is crucial for supporting students in their
academic journey. While there is a significant correlation between
homework and learning, the effectiveness of assignments is often
constrained by the large number of students and the extensive
grading required by teachers. In this context, open educational
resources (OER), particularly those built on the free and opensource Moodle platform, have shown increased learning among
students, becoming valuable instruments for educators. Automated
chemistry assignments are challenging, in contrast to physics or
mathematics. This is due to the necessity of accounting for the vast
yet finite universe of existing molecules, compounds, and reactions
́
along with the inherent constraints imposed within the field. In this article we present PLATA (Programa en Linea
de Apoyo a las
́
Tareas Académicas), a Moodle based OER for automated chemistry homework implemented at Facultad de Quimica
at UNAM.
PLATA is an online platform with more than 132 million open answer exercises (not multiple choice) automatically graded with
specific feedback for each exercise attempt. The design and characteristics of the program, some examples showing its versatility, and
the outstanding students’ outcomes of the OER are presented. PLATA has been used by more than 15,500 students over the past 4
years. The results displayed correspond to the 2022 academic year, with more than 3,200 students, from which 500 undergraduates
answered an exit survey, and we monitored the outcomes of 400 students. As a result, we can state that PLATA is a versatile, useful,
and robust program for chemistry assignments with a positive impact on students’ learning.
KEYWORDS: General Public, Inorganic Chemistry, Computer-Based Learning, Internet/Web-Based Learning,
Student-Centered Learning, Professional Development, Testing/Assessment
1. INTRODUCTION
heterogeneity of the school enrollment, are among the major
obstacles faced by first-year undergraduates.12
Academics have to overcome enormous challenges to reduce
students’ misconceptions and subsequently scholar dropoff.13−16 In order to transfer knowledge, teachers usually
need to provide rigorous methodologies, conceptual maps,
mental images, exercises, and examples related to industry or
basic research. Fostering a sense of group spirit that nurtures
community among university students is also essential, all
One of the most challenging aspects of learning sciences is its
inherent abstract nature, which compels students to transcribe
real world problems into modeled representations.1,2 Chemistry is not alien to this issue. In fact, there is a constant need to
relate macroscopic observations, submicroscopic or molecular
models and symbolic language that enables a simple, clear,
universal and synthetic way to communicate among chemists.3−9 The linkage between the three aspects of chemistry has
been already examined by Johnstone, who provided a
schematic representation known as Johnstone’s triangle,
broadly employed by several authors.5−11 Furthermore,
mathematical problems, including numerical and algebraic
determinations, the increased amount of work and work
rhythm going from high school to university courses, and the
© 2024 The Authors. Published by
American Chemical Society and Division
of Chemical Education, Inc.
Received: September 20, 2023
Revised: January 31, 2024
Accepted: February 2, 2024
Published: February 23, 2024
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while simultaneously assessing the degree of learning.13,16 In
addition, teachers should be at the forefront of cutting-edge
didactic technologies and approaches. These aspects contribute
to the stress, fatigue and emotional exhaustion experienced by
teachers, which are relevant factors in the development of
burn-out syndrome among faculty members.16−20
The significance of homework for learning chemistry has
been established in both traditional and flipped classrooms,
emphasizing the importance of practice in the learning
́
process.21−25 At Facultad de Quimica
at Universidad Nacional
Autónoma de México, UNAM, student enrollment has largely
increased in the past semesters, welcoming more than 1,650
students per year. Even though students are enrolled in one of
́
the 6 college majors offered by the Facultad de Quimica
(Chemistry, Chemical Engineering, Biological Pharmaceutical
Chemistry, Food Chemistry, Metallurgical Chemical Engineering, and Materials and Chemical Engineering), first-year
students have several common courses, such as General
Chemistry I and II. Indeed, teachers often contend with class
sizes of at least 70 students. Consequently, assigning,
evaluating, and grading assignments becomes an impossible
task. In practical terms, if an average teacher, typically handling
two to four groups, aimed to assign homework each week
throughout the semester, they would find themselves grading
more than five thousand classwork papers. If revising a single
classwork paper takes a minimum of 15 min, a teacher would
require 60 consecutive days, nonstop, to grade and evaluate all
of them. Clearly, this is an unattainable goal. Consequently,
teachers often resort to alternative methods such as handing
back corrected assignments and requesting students to selfgrade, minimizing homework by selecting the most illustrative
problems or seeking support from teaching assistants for the
grading process. In the worst-case scenarios, teachers do not
evaluate homework, depriving students from feedback or, even
worse, not leaving any assignments at all (Figure 1).
intricate, especially when teachers aim to avoid multiple-choice
questions.33,35−38 While mathematics or physics homework
can be programmed by varying only numerical values, resulting
in a practically infinite database in a short time, chemistry
needs to consider the vast yet finite universe of existing
molecules, compounds, and reactions along with the imposed
restrictions. Several factors must be considered, such as
solubility issues, the nonexistence of impossible molecules or
compounds, and the equilibrium constants governing reactions, among others. Herein, we present PLATA (“Programa
́
en Linea
de Apoyo a las Tareas Académicas”, www.
proyectoplata.com), an online platform for automated
chemistry homework hosted on Moodle. Noteworthy, Moodle
was selected as the OER platform primarily for its user-friendly
interface, visually ergonomic navigation, and the versatility
offered by its free open-source software, allowing a wide range
of mathematical functions and code writing.39 PLATA owes its
name to the Spanish acronym: Online Program for Academic
Homework Support, and also from the association with silver
(Plata in Spanish, Ag), a chemical element. This choice is
symbolic, reflecting Mexico’s prominent role as one of the
leading global silver producers. Over the past four years,
PLATA has been used by more than 15,500 students, proving
to be a robust, versatile, compatible, universal, easyimplemented, novel and efficient tool. PLATA places the
student in the center of their own learning, allowing
undergraduates to progress at different paces, in an
asynchronous manner, and independently from the teacher’s
grading and evaluation. Each of the 132 million free automated
exercises in PLATA provides unique and specific feedback,
including step-by-step procedures to solve the problem and
embedded external links to peer-reviewed videos,13 as well as
book chapters. Through this OER, undergraduates can
complete homework as many times as they need or want,
encountering similar exercises with different numerical values,
chemical compounds, and reactions.
Article
2. DESIGN OF PLATA
́́
At Facultad de Quimica
at UNAM, there are approximately
1,200 faculty members and more than 9,000 students enrolled
in one of the six college majors offered. Notably, the
Department of Inorganic and Nuclear Chemistry comprises
more than 46 permanent faculty members, including Full
Professors, Associate Professors, Technicians, and 52 part-time
Professors. The Department offers a variety of courses,
throughout the four-and-a-half-year program, serving over
4,000 students each semester, with the mission of contributing
to the development of chemists and responsible citizens.
Indeed, the Department offers seven theoretical and seven
experimental courses. To fulfill this crucial mission, the
́
Facultad de Quimica
strives to provide high-quality theoretical
classes and laboratories. Additionally, the institution maintains
competitive research groups dedicated to the development of
undergraduate, master’s, and Ph.D. students, along with
postdoctoral fellows. Among the various courses offered,
General Chemistry II, designed for first-year students, stands
out as one of the most challenging. In fact, it is among the top
́
five most frequently failed courses at Facultad de Quimica,
with an average failure rate of approximately 45% over the last
10 years out of more than 150 courses.
The project started in the fall of 2019, with the aim of
equipping students with tools to enhance their learning while
simultaneously alleviating teachers’ workload. In this context,
Figure 1. Challenges for general chemistry teachers at the Facultad de
́
Quimica.
In this context, the implementation of new technologies
represents an appealing alternative for educators. Novel
educational processes incorporating online learning have
been flourishing in the past decades, including collaborative,
mobile, cloud and game learning, among others.26,27
In science courses, the use of open educational resources
(OER) and virtual learning environments (VLE), particularly
those based on Moodle, has already proven to be an interesting
and valuable instrument for educators. In general, the
implementation of OER and VLE has been shown to enhance
students’ performance in final term exams, reduce the number
of drop-off students, foster great awareness on their learning
process, and promote self-sustained learning.16,22−38 Importantly, open educational resources, especially those on
chemistry topics, are not readily available in Spanish. The
development of automated chemistry assignments in contrast
to mathematics or physics homework, is substantially more
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Figure 2. General Chemistry II curricula and the partition into 13 homeworks (HW).
we design PLATA as an online platform of automated
chemistry assignments, specifically tailored for first-year
general chemistry courses, where approximately 3,200 students
are enrolled each semester. In particular, General Chemistry II
is an intricate course due the extensive curriculum and limited
teaching hours (2 h per week), together with a large student
enrollment. Consequently, this course was selected as the
initial course for automated assignments. The syllabus
comprises six blocks covering stoichiometry, chemical
equilibria, acid−base equilibria, solubility, and redox reactions.
These topics are covered in 32 lecture hours over 16 weeks,
divided into 16 two-hour sessions or 32 one-hour classes. With
three evaluations per semester, we prepared 13 assignments
corresponding to the topics illustrated in Figure 2.
Each educational program block is addressed by a minimum
of two assignments, with the difficulty level gradually
increasing. Every assignment consists of 10 questions and
can be attempted repeatedly based on the student’s preference
or necessity. Notably, the questions are not exclusively
multiple-choice; in fact, multiple-choice questions are rare in
PLATA, with the majority being formula-type questions.
Formula-type questions allow for variation of numeric values,
chemical compounds, and reactions. For example, in a question
related to acid−base equilibria, where students need to
determine the concentration of all species at equilibrium,
formula-type questions enable the modification of the acid’s
nature, its conjugated base, the associated acid dissociation
constant (Ka), and the initial concentration of the acid (Figure
3).
As shown in Figure 3, students have the option to repeat
their assignment with equivalent but distinct exercises. This
proves to be highly effective for practice, allowing students to
reinforce problem-solving methodologies without encountering identical exercises. It is important to notice that PLATA
does not consider any answer correct without its proper units,
emphasizing a fundamental pedagogical aspect. Every numerical value representing a physical or chemical quantity must be
accompanied by its corresponding unit.40 Noteworthy, PLATA
provides specific feedback for each attempt, enabling students
to identify the source of their mistakes in their particular case
(Figure 4). In addition, PLATA offers students supplementary
content for reviewing the course, including book chapters and
links to peer-reviewed videos.13
Afterward, the design of exercises can be as complex as
desired, allowing for the integration of different resolution
steps within a single problem. For example, a problem may
involve balancing chemical equations, determining the limiting
reactant, and addressing various questions about the system
(Figure 5.).
Taking advantage of the versatility of PLATA, we designed
assignments for other courses on the platform, including
Figure 3. Example of a formula-type question in PLATA. (a, b) Two
different essays. Automated modifications are highlighted in red. The
exercise is presented in English, but its original version is in Spanish
(see Supporting Information Figure S1).
General Chemistry I and Organometallic Chemistry. General
Chemistry I is the initial chemistry course imparted at Facultad
́
de Quimica
at UNAM, attracting more than 1,600 students
enrolled per semester. Unlike General Chemistry II, which
covers several algebraic and numeric concepts throughout the
semester, General Chemistry I is more focus on conceptual,
historical, and descriptive aspects. Despite this, PLATA
enabled the generation of 13 assignments, each containing
10 questions. These assignments encompass a variety of
exercises, including multiple-choice, true/false, numerical,
short answer, matching, and formula-type exercises. Once
again, each exercise created was accompanied by specific
feedback and linked to academic material for reviewing the
topic. The primary aim of coding this introductory course is to
standardize the knowledge base among students who come
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Figure 5. Example of an integral question in PLATA. Units, necessary
for answering correctly, are highlighted in red. The exercise is
presented in English, but its original version is in Spanish (see
Supporting Information Figure S3).
platform. PLATA was utilized as a training tool but was not
incorporated into the formal evaluation process.
We analyzed the outcomes of 408 students from five
different classes during the semester spanning from February
to June 2022, comparing their final exam results to their
engagement using PLATA. To accomplish this, we defined a
PLATA user as a student who completed a minimum of 8 out
of 13 assignments and successfully passed at least 4 of them.
Passing an assignment corresponds to a minimum grade of 6
out of 10. In fact, 74% of the students in these groups
completed at least 8 assignments, while 60% achieved favorable
grades in at least 4 of them. However, only 30% of the students
met both requirements. Applying these criteria, we observed
that 76% of users were successful in the final exam, while 79%
of nonusers failed the same examination (Figure 6). These
results clearly indicate that using PLATA as a training ground
and formative assessment is beneficial for the students,
enhancing their learning abilities and complementing the
didactic tools employed by each professor in the classroom.
We also monitored the frequency of access and use of
PLATA during the academic year 2022 for over 1,500 students.
As the semester progresses, the number of students using the
OER gradually decreases, while the average number of
attempts per quiz remains consistent (ca. 1.99 ± 0.18 attempts
per student). Indeed, the number of students using the
platform remained above 70% (out of 1551 students) during
the first two-thirds of the semester and then dropped to 35%
(Figure 7). The decrease in students’ involvement at this
particular point of the semester correlates with the timing of
the second evaluation. Students who have already failed one or
two partial evaluations may be compelled to take final exams,
and as a result they often drop the course. At Facultad de
́
Quimica,
it is common to have three partial evaluations during
Figure 4. Example of specific feedback in PLATA. Values and
compounds are highlighted in red in both the exercise enunciation
and the specific feedback. The exercise is presented in English, but its
original version is in Spanish (see Supporting Information Figure S2).
from diverse high schools across the country. In the context of
Organometallic Chemistry, our goal was to showcase the
versatility of PLATA by targeting upper-division students. For
this course, we had 26 students enrolled, and we generated 7
homework assignments, each with 5 questions. With these
three courses, we programmed 3,000 seed questions, resulting
in over 132 million displayed exercises over the last 4 years
(see Supporting Information).
3. STUDENTS’ OUTCOMES IN PLATA
In this section we will discuss some of the results gathered over
the last years during which PLATA has been fully operational
́
at the Facultad de Quimica.
We gained insight into the impact
of this virtual learning environment on student results by
comparing their scores in PLATA with their final course grades
within the academic year 2022. In that year, 3,232 students
were enrolled in the General Chemistry II course, with only
48% utilizing PLATA at least once. All students were
subscribed to the freely available Moodle uploaded OER.
The low participation rate may be attributed to various factors,
including limited student engagement or the fact that, in our
university, faculty members have academic autonomy, leading
to variations in the use of academic tools among different
teachers. To accurately assess students’ performance, we
selected five General Chemistry II classes taught by the
authors of this paper, resulting in a sample of ca. 400 students,
which represents 12% of the total student enrollment. In these
classes, teachers actively encouraged students to use the
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Figure 6. Academic outcomes of PLATA users and nonusers during the first semester of 2022 (February to June) in the General Chemistry II
course. A user is defined as a student who completed at least 8 out of 13 assignments and passed at least 4 assignments.
Figure 7. Frequency of PLATA use and students’ results over 2022. Semester 1: August 2021−January 2022. Semester 2: February 2022−June
2022. Grades are on a 0 to 10 scale. HW stands for homework.
Figure 8. Advantages of PLATA for different types of users: students, teachers, and the Faculty Department.
the semester. Depending on the results of those evaluations,
students may be exempt from final examinations. However, the
evaluation criteria depend on the professor teaching the class.
As shown in Figure 7, the average grades per homework are
satisfactory or good, except for assignments 8 and 10, which
correspond to the topics of buffer solutions and selective
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Figure 9. Students’ outcomes on the exit survey were evaluated on a scale from 1 to 10, where 1 represents “very poor” and 10 represents “very
high”.
precipitation, respectively. These two topics are challenging as
they require mastery of acid−base or precipitation equilibria
and the application of this knowledge to solve practical
problems. Identifying challenging subjects in the syllabus is a
key feature of PLATA.
As a matter of fact, we alerted the Department to explore
potential solutions, including reviewing the difficulty of these
specific exercises, reinforcing the aforementioned topics during
lectures, creating additional support content for the students,
and emphasizing the importance of solving these assignments
(Figure 8). Indeed, the results gathered through the use of
PLATA enabled internal discussion with the Department
regarding the development of a new curriculum for the General
Chemistry II course. Based on the platform’s results we
proposed an increase in lecture hours to enable teachers to
delve deeper into explanations on certain topics, particularly
the application of buffer solutions and selective precipitation.
Moreover, the proposal includes the development of
interactive teaching tools to assist students in understanding
these topics.
An exit survey was conducted with nearly 500 PLATA users
to evaluate their perception of the proposed tool (the quiz and
all results are available in the Supporting Information). In
general, students expressed high satisfaction with PLATA,
highlighting its usefulness, variety of exercises, and overall
difficulty (Figure 9). We observed that 87% of students found
PLATA to be a useful learning tool, rating it higher than 7 out
of 10 for the variety of exercises and indicating that the level of
difficulty was moderate. In addition, over 70% of students
considered it accessible, expressed a willingness to recommend
it to fellow undergraduates, and expressed a desire to have this
instrument available in other courses.
We collected comments from students at the end of the
semester (Figure 10). Overall, students expressed satisfaction
with their experience using PLATA. Many found the Open
Educational Resource to be highly beneficial for studying
throughout the semester and emphasized the importance of
specific feedback for each exercise. Nevertheless, a significant
number of students raised concerns about the narrow range for
Figure 10. Students’ outcomes on the exit survey.
correct answers and the lack of respect for significant figures in
the calculated numbers. PLATA users expressed frustration
with these issues. To address this feedback, we have adjusted
the correct answer’s interval to allow for numeric values within
a 5% margin of error. Additionally, we have introduced a
contact email address to receive and address comments and/or
complaints from students. Representative comments have been
translated and are provided below:
• I found the idea of PLATA very good; I like that the
number of attempts is not limited, and that feedback shows
the precise procedure to solve the problem immediately.
However, it is very strict with notation, allowing one correct
unit for each exercise. I think it is great for studying.
• The interval of correct answers should be more f lexible;
sometimes I consider one decimal and it marked me wrong. I
also spent a lot of time learning how to write numbers with
powers of ten.
• Honestly, I was delighted with PLATA; it helps me a lot for
understanding topics that we covered quickly in lectures. I
appreciate that the procedure is always very detailed and
that I could try as much as I wanted until I felt comfortable
with the topics.
• I like the project and I think is very usef ul. However, I felt
f rustrated many times because the platform penalizes
rounding up numeric values. I also think that it would be
great to have isolated exercises and not have to complete all
the homework to get feedback.
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engage in 480 h of work over a period of six to 12 months.
According to Mexico’s Ministry of Public Education
(Secretariá de Educación Pública, SEP) approximately
780,000 higher education students complete more than 375
million hours of Social Service every year.44 Recently, PLATA
has been incorporated as a Social Service program for last-year
undergraduate students interested in the production of
educational material. At present, PLATA has two students
involved in the program, each of them in charge of creating
complementary material for the General Chemistry II course
focused on titration experiments and determination of
concentrations at equilibrium. This means that, in addition
to the 132 million exercises already available, the database can
continue to expand and cover topics that are equally important
and interesting for students, especially in the laboratory area
where manual skills can be complemented with numerical
exercises. This demonstrates that PLATA still has a lot to offer,
and as will be seen below, it can be useful for more courses.
PLATA can also be seen as a means to bolster team building
and facilitate the development and nurturing of a sense of
community among students. Indeed, the platform will evolve
to be by the students, for the students. This way, undergraduates may feel like an important part of the project.
• The project is great. I feel that my ability to solve problems
has increase, and that makes me very happy.
• I was very pleased with the platform. Will it be available in
other courses soon? Sometimes I found small errors, how can
I contact you?
4. OTHER IMPORTANT FEATURES OF PLATA
PLATA during the COVID-19 Pandemic
The SARS-COV-2 global pandemic, which started at the end
of 2019, compelled each one of us to adopt to a new lifestyle.41
The government’s strategy to control this pandemic has
required the population to maintain a mutual healthy distance
and stay at home. This has had evident negative effects on
education, in particular, the teaching of chemistry, as
laboratories constitute an essential source of knowledge. At
́
the Facultad de Quimica
at UNAM, the suspension of face-toface classes began on March 2020 and ended in March 2022.
During this two year period, a large number of students were
required to attend virtual classes. In this context, PLATA,
which was already installed and fully functional at the Facultad
́
de Quimica,
served as an important tool for both teachers and
students. It allowed all members of our community to access a
free, asynchronous, and personalized problem-solving platform
with supporting content for their courses. It is important to
notice that several students were assigned supplementary tasks
at home during this period, leading them to focus on their
studies late at night. In this sense, the implementation of
asynchronous instruments was fundamental.
During the COVID-19 global health crisis, a major concern
among teachers was the need to prevent students from
cheating on examinations. To address this issue, a group of
professors planned exams on PLATA taking advantage of the
program-based questions. Indeed, a typical exam uploaded to
the platform consisted of 15 questions, each with at least 4
variable parameters. In addition, each quiz is presented with
sequential navigation; i.e., students cannot go back to previous
questions. The questions are also shuffled, so the order in
which they appear to the student is randomized. Taking this
into account, the probability of two students having the same
question is less than 0.000017%. As a result, PLATA proved to
be an incorruptible tool for examinations and was used for this
purpose. The main difficulties encountered by the students
were technical issues with their Internet network providers
during examinations, which, in some rare cases, resulted in
disconnection and thus truncated evaluations. Nevertheless,
while PLATA proved valuable as an assessment platform, we
maintain that its most potent use remains as a tool for
assignments, primarily due to the invaluable feedback it offers.
The Future of PLATA
The undeniable success of PLATA has motivated the authors
of this contribution to explore different directions and harness
its full potential. First, we will continue the ongoing work to
correct and improve the current platform. Students, who are
starting to get involved, along with teachers, will continuously
make efforts to enhance the existing database of exercises as
well as address technical and aesthetical issues. Additionally,
we will expand the scope of the OER platform to other
courses, particularly those in which first-year students struggle
the most: Introduction to Algebra, Calculus, Physics,
Thermodynamics, and Analytical Chemistry. Considering the
experience already gathered, we believe that these new courses
could be prepared in a short time. In fact, members of the
Physics and Theoretical Chemistry Department, Physical
Chemistry Department and Analytical Chemistry Department
́
at Facultad de Quimica
have recently started implementing
PLATA for Physics I, Thermodynamics and Analytical
Chemistry I courses, respectively.
Another interesting feature will involve the creation of
courses designed for high school students interested in
pursuing one of the six chemistry bachelor’s programs at the
́
Facultad de Quimica.
These courses aim to assist high school
students in preparing for the often challenging first year of
college. In reality, incoming freshmen often require some
adjustment time when transitioning to college life, primarily
due to advanced content and increased workload.
By utilizing PLATA prior to their enrollment, prospective
university students can identify their weaknesses and address
them before embarking on their college journey. At the
́
Facultad de Quimica,
approximately 50% of first-semester
students typically encounter difficulties in at least one course.
We firmly believe that implementing PLATA for preundergraduate students can play a crucial role in mitigating this high
failure rate.
Indeed, the Analytical Chemistry I course is taught in the
second term of the second academic year, creating almost a six
month gap after General Chemistry II. This gap is often
considered, among students and staff, a likely cause of lower
PLATA as a Social Service
The Universidad Nacional Autónoma de México (UNAM) is a
public institution dedicated to contributing to the common
good by educating socially responsible citizens.42,43 In this
context, Mexico is one of the few countries that requires
students enrolled in higher education programs to participate
in a mandatory Social Service program.40 Social Service is
similar to the Community Service required in some American
schools; however, in Mexico, social service activities must be
directly related to the student’s field of study. In Mexico, Social
Service programs play a critical role, benefiting marginalized
segments of society and fostering students’ awareness, making
them more aware and socially responsible. Typically, students
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Figure 11. continued
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Figure 11. Example of the generation of a formula-type question.
Computational Details and Areas for Improvement
grades in Analytical Chemistry I, as many of the relevant
concepts and skills taught in General Chemistry II are essential
for understanding this subsequent course. During a pilot trial, a
class of 58 Analytical Chemistry I students were given access to
a smaller subset of PLATA problems selected to help them
review key concepts and skills. Students were required to
provide evidence of visiting the platform, but the scores on the
problems were not factored into the overall grade. This
allowed students the flexibility to engage with the content to
the extent they personally preferred. The results of this trial
show that PLATA can serve as a predictive tool for student
performance. The final grade of each student was compared
with the grade obtained in the PLATA problem set. As
expected, students with good performances in PLATA
obtained high grades in their final exams, whereas those who
failed the assignments also failed the course (see Figure S4 in
the Supporting Information). A second trial is currently being
conducted to assess whether these results hold up with
different sets of students. Before long, a thorough statistical
analysis will be conducted to clearly demonstrate the
correlation between the use of PLATA and students’
performance, which will be an interesting avenue for future
research.
A typical formula-type question is built with four main
components: random variables, global variables, the question
itself, and feedback. The random variable allows the generation
of random values, such as pressure, temperature, or
concentration, as well as random numbers used within the
global variables. The global variables are strings of text or
values corresponding to different compounds and their
associated equilibrium constants. The randomly generated
value n allows the selection of the n object from the string in
the global variables. This permits variation among substances
or chemical equations and their related equilibrium constants
or molar masses, for example. The question section calls
objects from the strings, generating a new question each time a
student attempts it. Finally, the feedback section uses the
values and strings from the random and global variables to
provide a detailed explanation of the exercise resolution. We
present an example of the generation of a formula-type
question in Figure 11.
As a result, the screen in Figure 12 is presented to the
student.
The PLATA task group is currently in the process of
transitioning to Python programming to unlock various
capabilities and reduce server time usage. Through this
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Article
They can learn both from the specific feedback provided by the
exercises and from books and videos embedded in the
assignments. Contrary to other platforms, PLATA is
programmed to randomly modify not only numeric values
but also chemical substances, chemical reactions, and
equilibrium constants that are related with one another and
cannot vary independently. This has generated more than 132
million exercises. PLATA provides students with assignments
for general chemistry and upper-division courses. Its versatility
and robustness have empowered students to practice, study,
improve and learn independently. In academic terms, results
clearly showed that students who used PLATA regularly had
better performance in the final examinations compared to
those who did not (76% users passed the final examination,
while only 21% of nonusers passed). Moreover, our OER could
be used for examinations, even for a large number of students;
however, we believe that it is more powerful as a training tool
and for formative assessment. In an exit survey, students
expressed that PLATA is an easy-to-access, valuable, and useful
instrument for undergraduates and educators. Furthermore,
they expressed a desire to see it implemented in other courses.
The future of PLATA is secured and exciting, with many
opportunities for platform development now available. We
strongly believe that PLATA is a versatile, robust, compatible,
universal, and efficient open educational resource, an instrument that will have a significant impact on the education of the
next generations of chemists in our university.
■
ASSOCIATED CONTENT
sı Supporting Information
*
The Supporting Information is available at https://pubs.acs.org/doi/10.1021/acs.jchemed.3c00962.
Different questions and results on the survey (PDF)
(DOCX)
■
AUTHOR INFORMATION
Corresponding Authors
Miguel Reina − Departamento de Química Inorgánica y
Nuclear, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0003-4959-4105; Email: mreina.2404@
quimica.unam.mx
Eduardo Gabriel Guzmán-López − Departamento de
Química, Universidad Autónoma Metropolitana Unidad
Iztapalapa, 09340 Ciudad de México, México; orcid.org/
0000-0003-1443-4136; Email: [email protected]
Antonio Reina − Departamento de Química Inorgánica y
Nuclear, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0001-7527-7176;
Email: [email protected]
Figure 12. Students view of a programmed formula-type question.
approach, there will no longer be a need for strings as Python
can access existing and more comprehensive databases, thereby
expanding the range of substances and reactions accessible
within PLATA. Additionally, this shift will enable the inclusion
of embedded chemical structure drawing tools, making it easier
to create more intricate problem-solving exercises.
Authors
César Guzmán-López − Departamento de Química,
Universidad Autónoma Metropolitana Unidad Iztapalapa,
09340 Ciudad de México, México
Carlos Hernández-Garciadiego − Instituto de Matemáticas,
Universidad Nacional Autónoma de México, 04510 Ciudad
de México, México
María de los Á ngeles Olvera-León − Departamento de
Química Inorgánica y Nuclear, Facultad de Química,
5. CONCLUSIONS
PLATA is a novel open educational resource uploaded on
Moodle that enables students to practice by problem-solving.
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pubs.acs.org/jchemeduc
■
Universidad Nacional Autónoma de México, 04510 Ciudad
de México, México
Mario Alfredo Garcia-Carrillo − Departamento de Química
Orgánica, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México
Marco Antonio Tafoya-Rodríguez − Departamento de
Química Inorgánica y Nuclear, Facultad de Química,
Universidad Nacional Autónoma de México, 04510 Ciudad
de México, México
Victor Manuel Ugalde-Saldívar − Departamento de Química
Inorgánica y Nuclear, Facultad de Química, Universidad
Nacional Autónoma de México, 04510 Ciudad de México,
México; orcid.org/0000-0002-9625-8713
Itzel Guerrero-Ríos − Departamento de Química Inorgánica y
Nuclear, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0003-1741-9425
Laura Gasque − Departamento de Química Inorgánica y
Nuclear, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0001-9013-4771
Jorge M. del Campo − Departamento de Física y Química
Teórica, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0002-4195-3487
Daniela Franco-Bodek − Departamento de Química
Analítica, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México;
orcid.org/0000-0003-4841-3819
Rolando Bernal-Pérez − Secretaría Académica de Docencia,
Facultad de Química, Universidad Nacional Autónoma de
México, 04510 Ciudad de México, México
Milton Medeiros − Departamento de Fisicoquímica, Facultad
de Química, Universidad Nacional Autónoma de México,
04510 Ciudad de México, México; orcid.org/0000-00019317-9270
Armando Marín-Becerra − Departamento de Química
Inorgánica y Nuclear, Facultad de Química, Universidad
Nacional Autónoma de México, 04510 Ciudad de México,
México
Héctor García-Ortega − Departamento de Química Orgánica,
Facultad de Química, Universidad Nacional Autónoma de
México, 04510 Ciudad de México, México
Jesús Gracia-Mora − Departamento de Química Inorgánica y
Nuclear, Facultad de Química, Universidad Nacional
Autónoma de México, 04510 Ciudad de México, México
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Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.jchemed.3c00962
Notes
The authors declare no competing financial interest.
■
Article
ACKNOWLEDGMENTS
This work has been carried out with the support of the
UNAM-DGAPA-PAPIME Program-PE203123. The authors
thank the meaningful discussions with all the faculty members
and students, especially to Dra. Karla Salas-Martin (FQ,
UNAM), M. en C. Adrián Espinoza-Guillén (Laboratorio de
Química Inorgánica Medicinal, FQ, UNAM), Dr. Bruno
Landeros Rivera (FQ, UNAM), and Dr. Mario RodríguezVarela (Laboratorio Universitario de Nanotecnología Ambiental, ICAT, UNAM).
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