<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>2448-8089</journal-id>
<journal-title><![CDATA[Educación matemática]]></journal-title>
<abbrev-journal-title><![CDATA[Educ. mat.]]></abbrev-journal-title>
<issn>2448-8089</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Investigación y Divulgación de la Educación Matemática A.C.; Universidad de Guadalajara]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S2448-80892016000300217</article-id>
<article-id pub-id-type="doi">10.24844/em2803.08</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[El concepto de variable: un análisis con estudiantes de bachillerato]]></article-title>
<article-title xml:lang="en"><![CDATA[The variable concept: an analysis with high school students]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Herrera López]]></surname>
<given-names><![CDATA[Heli]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cuesta Borges]]></surname>
<given-names><![CDATA[Abraham]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Escalante Vega]]></surname>
<given-names><![CDATA[Juana Elisa]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Dirección General de Bachillerato  ]]></institution>
<addr-line><![CDATA[Xalapa Veracruz]]></addr-line>
<country>México</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Veracruzana Facultad de Economía ]]></institution>
<addr-line><![CDATA[Xalapa Veracruz]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad Veracruzana Facultad de Estadística e Informática ]]></institution>
<addr-line><![CDATA[Xalapa Veracruz]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2016</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2016</year>
</pub-date>
<volume>28</volume>
<numero>3</numero>
<fpage>217</fpage>
<lpage>240</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S2448-80892016000300217&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S2448-80892016000300217&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S2448-80892016000300217&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen: El artículo analiza los resultados de los modos de resolución de 48 estudiantes, pertenecientes a tres niveles diferentes de enseñanza en bachillerato, cuando responden a problemas donde se manifiestan procesos de generalización y de modelación a través de la relación del lenguaje algebraico con los lenguajes figural, natural y aritmético. Empleando el Modelo 3uv (3 Usos de la variable) se describen, tanto la comprensión de los diferentes aspectos que caracterizan la variable como las actuaciones de los estudiantes cuando se enfrentan a tareas.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract: This article analyze the results of the resolutions mode of 48 students from three different levels of learning in high school, when they try to solve problems that involve generalization and modeling process through the relation between algebraic language with figurative, natural and arithmetic language. Using the 3uv Model (3 uses of the variable) to describe the comprehension of the different aspects that characterize the variable as the acting of the students when they face tasks.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[educación matemática]]></kwd>
<kwd lng="es"><![CDATA[dificultades]]></kwd>
<kwd lng="es"><![CDATA[enseñanza en bachillerato]]></kwd>
<kwd lng="es"><![CDATA[pensamiento algebraico]]></kwd>
<kwd lng="es"><![CDATA[variables]]></kwd>
<kwd lng="en"><![CDATA[mathematical education]]></kwd>
<kwd lng="en"><![CDATA[difficulties]]></kwd>
<kwd lng="en"><![CDATA[high school teaching]]></kwd>
<kwd lng="en"><![CDATA[algebraic thinking]]></kwd>
<kwd lng="en"><![CDATA[variables]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Bednarz]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Janvier]]></surname>
<given-names><![CDATA[B.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Emergence and Development of Algebra as a Problem-solving Tool: Continuities and Discontinuities with Arithmetic]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Bednarz]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Kieran]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Lee]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Approaches to Algebra]]></source>
<year>1996</year>
<page-range>115-36</page-range><publisher-loc><![CDATA[Dordrecht, The Netherlands ]]></publisher-loc>
<publisher-name><![CDATA[Kluwer Academic Publishers]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B2">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Booth]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Algebra: Children's Strategies and Errors]]></source>
<year>1984</year>
<publisher-loc><![CDATA[Windsor ]]></publisher-loc>
<publisher-name><![CDATA[NFER-Nelson]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B3">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Castro]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Castro]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Representaciones y modelización]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[La educación matemática en la enseñanza secundaria]]></source>
<year>1997</year>
<page-range>95-124</page-range><publisher-loc><![CDATA[Barcelona, España ]]></publisher-loc>
<publisher-name><![CDATA[Horsori]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B4">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cohen]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Manion]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Morrison]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
</person-group>
<source><![CDATA[Research methods in education]]></source>
<year>2011</year>
<publisher-loc><![CDATA[Londres, Reino Unido ]]></publisher-loc>
<publisher-name><![CDATA[Routledge]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cuervo]]></surname>
<given-names><![CDATA[R. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Diccionario de construcción y régimen de la lengua castellana (Tomo II)]]></source>
<year>1988</year>
<publisher-loc><![CDATA[Barcelona, España ]]></publisher-loc>
<publisher-name><![CDATA[Herder]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B6">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Duval]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Semiosis y noesis]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Sánchez]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Zubieta]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<source><![CDATA[Lecturas en didáctica de la matemática: Escuela Francesa]]></source>
<year>1993</year>
<page-range>118-44</page-range><publisher-loc><![CDATA[México ]]></publisher-loc>
<publisher-name><![CDATA[Sección de Matemática Educativa CINVESTAV-IPN]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Duval]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Quel cognitif retenir en didactique des mathematiques?]]></article-title>
<source><![CDATA[Recherches en Didactique des Mathematiques]]></source>
<year>1996</year>
<volume>16</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>349-82</page-range></nlm-citation>
</ref>
<ref id="B8">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Duval]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Semiosis y pensamiento humano. Registros semióticos de aprendizajes intelectuales]]></source>
<year>1999</year>
<publisher-loc><![CDATA[Cali. Colombia ]]></publisher-loc>
<publisher-name><![CDATA[Universidad del Valle]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B9">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Escalante]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Cuesta]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Dificultades para comprender el concepto de variable: un estudio con estudiantes universitarios]]></article-title>
<source><![CDATA[Educación Matemática]]></source>
<year>2013</year>
<volume>24</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>5-30</page-range></nlm-citation>
</ref>
<ref id="B10">
<nlm-citation citation-type="confpro">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Filloy]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Rojano]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
<name>
<surname><![CDATA[Streefland]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Obstructions to the Acquisition of Elemental Algebraic Concepts and Teaching Strategies]]></source>
<year>1985</year>
<volume>1</volume>
<conf-name><![CDATA[ Proceedings of the Ninth International Conference for the Psychology of Mathematics Education]]></conf-name>
<conf-loc> </conf-loc>
<page-range>154-8</page-range></nlm-citation>
</ref>
<ref id="B11">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Filloy]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
</person-group>
<source><![CDATA[Aspectos teóricos del álgebra educativa]]></source>
<year>1999</year>
<publisher-loc><![CDATA[México ]]></publisher-loc>
<publisher-name><![CDATA[Grupo Editorial Iberoamérica]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B12">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[García]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Segovia]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Lupiáñez]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Antecedentes y fundamentación de una investigación sobre errores en la resolución de tareas algebraicas]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Arnau]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Lupiáñez]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Maz]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<source><![CDATA[Investigaciones en pensamiento numérico y algebraico e historia de la matemática y educación matemática 2012]]></source>
<year>2012</year>
<page-range>139-48</page-range><publisher-loc><![CDATA[Valencia, España ]]></publisher-loc>
<publisher-name><![CDATA[Departamento de Didáctica de la Matemática de la Universitat de València y SEIEM]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Guzmán]]></surname>
<given-names><![CDATA[R. I.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Registros de representación, el aprendizaje de nociones relativas a funciones: voces del estudiante]]></article-title>
<source><![CDATA[RELIME]]></source>
<year>1998</year>
<volume>1</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>5-21</page-range></nlm-citation>
</ref>
<ref id="B14">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hitt]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[El papel de los esquemas, las conexiones y las representaciones internas y externas dentro de un Proyecto de Investigación en Educación Matemática]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Gómez]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Iniciación a la investigación en didáctica de la matemática. Homenaje al profesor Mauricio Castro]]></source>
<year>2001</year>
<page-range>165-77</page-range><publisher-loc><![CDATA[Granada, España ]]></publisher-loc>
<publisher-name><![CDATA[Universidad de Granada]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B15">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Juárez]]></surname>
<given-names><![CDATA[J. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Dificultades en la interpretación del concepto de variable en profesores de matemáticas de secundaria: un análisis mediante el modelo 3uv]]></article-title>
<source><![CDATA[Números. Revista de la Didáctica de las Matemáticas]]></source>
<year>2011</year>
<volume>76</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>83-103</page-range></nlm-citation>
</ref>
<ref id="B16">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Kieran]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Filloy]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[El aprendizaje del álgebra escolar desde una perspectiva psicológica]]></article-title>
<source><![CDATA[Enseñanza de las Ciencias]]></source>
<year>1989</year>
<volume>7</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>229-40</page-range></nlm-citation>
</ref>
<ref id="B17">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Martí]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Pozo]]></surname>
<given-names><![CDATA[J. I.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Más allá de las representaciones mentales: la adquisición de los sistemas externos de representación]]></article-title>
<source><![CDATA[Infancia y aprendizaje]]></source>
<year>2000</year>
<volume>23</volume>
<numero>90</numero>
<issue>90</issue>
<page-range>11-30</page-range></nlm-citation>
</ref>
<ref id="B18">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Montes]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
</person-group>
<source><![CDATA[Iniciación al álgebra a través de la variable: una aplicación didáctica del modelo 3uv]]></source>
<year>2003</year>
<publisher-loc><![CDATA[México ]]></publisher-loc>
<publisher-name><![CDATA[DME, Cinvestav]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B19">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ochoviet]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Oktac]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Algunos aspectos del desarrollo del pensamiento algebraico: el concepto de raíz y de variable en ecuaciones polinómicas de segundo grado. Un estudio de casos realizado con estudiantes uruguayos de enseñanza secundaria]]></article-title>
<source><![CDATA[Educación Matemática]]></source>
<year>2011</year>
<volume>23</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>99-121</page-range></nlm-citation>
</ref>
<ref id="B20">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Radford]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[The Roles of Geometry and Arithmetic in the Development of Algebra: Historical Remarks from a Didactic Perspective]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Bednarz]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Kieran]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Lee]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Approaches to Algebra. Perspectives for Research and Teaching]]></source>
<year>1996</year>
<page-range>39-53</page-range><publisher-loc><![CDATA[Dordrecht, The Netherlands ]]></publisher-loc>
<publisher-name><![CDATA[Kluwer Academic Publishers]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B21">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Sobre las nociones de representación y comprensión en la investigación en Educación Matemática]]></article-title>
<source><![CDATA[PNA]]></source>
<year>2009</year>
<volume>4</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>1-14</page-range></nlm-citation>
</ref>
<ref id="B22">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Lupiáñez]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Objetivos y competencias en el aprendizaje de los números naturales]]></article-title>
<source><![CDATA[Uno. Revista de Didáctica de la Matemática]]></source>
<year>2010</year>
<volume>54</volume>
<page-range>14-30</page-range></nlm-citation>
</ref>
<ref id="B23">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Fernández-Cano]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Análisis didáctico y metodología de investigación]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Lupiáñez]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Molina]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Análisis didáctico en educación matemática]]></source>
<year>2013</year>
<page-range>1-22</page-range><publisher-loc><![CDATA[Granada, España ]]></publisher-loc>
<publisher-name><![CDATA[Comares]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B24">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Socas]]></surname>
<given-names><![CDATA[M. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Palarea]]></surname>
<given-names><![CDATA[M. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Hernández]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Dificultades y uso de los recursos algebraicos de estudiantes para maestros de educación primaria]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Rico]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Cañadas]]></surname>
<given-names><![CDATA[M. C.]]></given-names>
</name>
<name>
<surname><![CDATA[Gutiérrez]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Molina]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Segovia]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
</person-group>
<source><![CDATA[Investigación en Didáctica de la Matemática. Homenaje a Encarnación Castro]]></source>
<year>2013</year>
<page-range>95-102</page-range><publisher-loc><![CDATA[Granada, España ]]></publisher-loc>
<publisher-name><![CDATA[Comares]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B25">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Trigueros]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Ursini]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[First-year Undergraduates' Difficulties in Working with Different Uses of Variable]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Selden]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Dubinsky]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Harel]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Hitt]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
</person-group>
<source><![CDATA[CBMS Research in Collegiate Mathematics Education]]></source>
<year>2003</year>
<volume>12</volume>
<page-range>1-29</page-range></nlm-citation>
</ref>
<ref id="B26">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ursini]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Escareño]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
<name>
<surname><![CDATA[Montes]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Trigueros]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Enseñanza del álgebra elemental. Una propuesta alternativa]]></source>
<year>2005</year>
<publisher-loc><![CDATA[México ]]></publisher-loc>
<publisher-name><![CDATA[Trillas]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B27">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ursini]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Trigueros]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[¿Mejora la comprensión del concepto de variable cuando los estudiantes estudian matemáticas avanzadas?]]></article-title>
<source><![CDATA[Educación Matemática]]></source>
<year>2006</year>
<volume>18</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>5-38</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
