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EVOLUTION OF ALTERNATIVE CONCEPTIONS ON
PURE SUBSTANCES AND MIXTURES OF PRIMARY
EDUCATION STUDENTS’
Florentina Cañada, César Pizarro*, Lina Melo, Javier Cubero,
María José Arévalo
Department of Sciences and Mathematics Education
University of Extremadura (Spain)
E-mail:[email protected]
International Workshop
“SCIENCE EDUCATION AND GUIDANCE IN SCHOOLS:
THE WAY FORWARD”
Firenze, 21-22 October, 2013
Summary
1. Introduction
Alternative conceptions
Alternative conceptions reports on material systems at Primary education
Work goals
2. Methodology
3. Results and discussion
4. Conclusions
1. INTRODUCTION
The recognition of the diversity of matter is a fundamental goal of teaching
chemistry1.
Material systems are introduced at Primary Education and they are studied
more in depth in the Secondary Education.
Students have ideas on scientific contents which are often misleading and
confusing. Those ideas are called alternative conceptions.
1Martínez Losada et al., 2009. What students of primary and secondary know about material systems? How to treat it in textbooks? Revista electrónica de enseñanza de las ciencias, 8: 137-155
1. INTRODUCTION
Detect alternative conceptions in student of third stage of Primary Education on pure substances and mixtures and to develop an educational instruction to help overcome these ideas.
The recognition of the diversity of matter is a fundamental goal of teaching
chemistry (Martínez Losada et al., 2009).
Material systems are introduced at Primary Education and they are studied
more in depth in the Secondary Education.
Students have ideas on scientific contents which are often misleading and
confusing. Those ideas are called alternative conceptions.
This work aims to
Alternative conceptions
Mental representations of the world that allow to understand the environment and to act according to them
Scientifically incorrect
Persistent to change
Universality
Alternative conceptions
Mental representations of the world that allow to understand the environment and to act according to them
These conceptions lead to conceptual mistakes and are an obstacle in learning scientifically correct concepts
Scientifically incorrect
Persistent to change
Universality
They must be considered during the educational process to ease significant learning
Alternative conceptions reports on material systems at Primary education
Confusion between pure substance and homogeneous mixture
Students match mixture with processed material
Pure substance is identified with natural origin
Martín del Pozo, Galán Martín (2012)
Martínez Losada et al. (2009)
Natural origin prevails over perception
Work goals
1. Identify alternative conceptions of students in the third stage of Primary Education on material systems (pure substances and mixtures)
2. Design teaching tools to overcome of alternative conceptions
RESEARCH METHOD
DESCRIPTIVE AND INTERPRETATIVE METHODOLOGY
SAMPLE SELECTION 21 STUDENTS 5 PRIMARY 21 STUDENTS 5TH PRIMARY EDUCATION (Age: 10 – 11
years)
DATA INTSTRUMENT QUESTIONNAIRE
2. METHODOLOGY
RESEARCH METHOD
DESCRIPTIVE AND INTERPRETATIVE METHODOLOGY
SAMPLE SELECTION 21 STUDENTS 5 PRIMARY 21 STUDENTS 5TH PRIMARY EDUCATION (Age: 10 – 11
years)
DATA INTSTRUMENT QUESTIONNAIRE
2. METHODOLOGY
1. Mixing water and oil, the result is a mixture: [ ] Homogeneous [ ] Heterogeneous. Why?1 2. Milk is: [ ] A pure substance [ ] A mixture. Why?1 3. Classify these products as “pure substance” or “mixture”: yoghurt, salt, coke, diamond,
water, copper, ice, iron, oil, granite stone, silver, and sand. Justify your election2.
(1Martínez Losada et al., 2009; 2Martín del Pozo and Galán Martín, 2011)
DEVELOPMENT
4 WEEKS
2. METHODOLOGY
Students completed questionnaire in the class
Detection of alternative conceptions Planning instruction in basis of the
results
1st, 2nd week
DEVELOPMENT
4 WEEKS
2. METHODOLOGY
2 Session class
3rd week
Explanation of key concepts
Theorical (1 h)
PowerPoint
Practice (1 h)
students-teacher Interaction
Taking into account
Pre-test results
Students’ textbook
2. METHODOLOGY
Explanation of key concepts
Theorical (1 h)
PowerPoint
Practice (1 h)
Chemistry workshop
students-teacher Interaction
Implementation of the acquired knowledge
Cooperative work
Taking into account
Pre-test results
Students’ textbook
2. METHODOLOGY
Practice phase
Groups of 4-5 students
Cooperative work
Group notebook
Activities
Classify
Pure substance/mixture
Mix Experiment
Homogeneous/heterogeneous milk
DEVELOPMENT
4 WEEKS
2. METHODOLOGY
4th week
3. RESULTS AND DISCUSSION 1. Mixing water and oil: homogeneous or heterogeneous?
1. Mixing water and oil: homogeneous or heterogeneous?
*
3. RESULTS AND DISCUSSION 1. Mixing water and oil: homogeneous or heterogeneous?
1. Mixing water and oil: homogeneous or heterogeneous?
*
25%
3. RESULTS AND DISCUSSION
AFT
ER IN
STR
UC
TIO
N
1. Mixing water and oil: homogeneous or heterogeneous?
1. Mixing water and oil: homogeneous or heterogeneous?
*
95%
STUDENTS SELECTING HOMOGENEOUS: JUSTIFICATIONS
STUDENTS SELECTING HOMOGENEOUS: JUSTIFICATIONS
Analysing justifications question 1:
Before instruction: “Incorrect classification, correct justification”
Students know substances remain separate but don’t match with correct criterion
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
Analysing justifications question 1:
Before instruction: Just one student gave the correct argumentation
*
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
Analysing justifications question 1:
Before instruction: Just one student gave the correct argumentation After instruction : correct argumentation increases up to 40%
*
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
Analysing justifications question 1:
Before instruction: Just one student gave the correct argumentation After instruction : correct argumentation increases up to 40% But, 30% justified in base to the different density
CONFUSE DENSITY AND VISCOSITY, THEY DON’T KNOW THE IMMISCIBILITY CONCEPT
*
3. RESULTS AND DISCUSSION 2. Milk is: a pure substance or a mixture?
2. Milk is: a pure substance or a mixture?
*
3. RESULTS AND DISCUSSION 2. Milk is: a pure substance or a mixture?
2. Milk is: a pure substance or a mixture?
*
14%
3. RESULTS AND DISCUSSION 2. Milk is: a pure substance or a mixture?
2. Milk is: a pure substance or a mixture?
AFT
ER IN
STR
UC
TIO
N
*
66%
STUDENTS SELECTING PURE SUBSTANCE: JUSTIFICATIONS
STUDENTS SELECTING PURE SUBSTANCE: JUSTIFICATIONS
Analysing justifications question 2:
Before instruction “Because milk comes from a cow” “Because a mixture is to mix something and milk is natural” Milk components cannot be distinguished
CONFUSE: NATURAL WITH PURE
STUDENTS SELECTING MIXTURE: JUSTIFICATIONS
STUDENTS SELECTING MIXTURE: JUSTIFICATIONS
Analysing justifications question 2:
Before instruction, nobody gave a correct argumentations After instruction “Milk is a mixture because is formed by several components”
*
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
1. YOGHURT 2. SALT 3. COKE 4. DIAMOND 5. WATER 6. COPPER
7. ICE 8. IRON 9. OIL 10. GRANITE
STONE
11. SILVER 12. SAND
Pure Substance
Because…
Mixtures
Because…
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Pure substance Before instruction
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Pure substance
- Materials used in a processed way
Before instruction
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Pure substance After instruction
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Pure substance After instruction
Analysing justifications question 3:
PURE SUBSTANCES: JUSTIFICATIONS
PURE SUBSTANCES: JUSTIFICATIONS
Before instruction, the origin (natural or manufactured) notion remains versus composition
*
Analysing justifications question 3:
PURE SUBSTANCES: ARGUMENTATION
PURE SUBSTANCES: ARGUMENTATION
*
Before instruction, the origin (natural or manufactured) notion remains versus composition After instruction, correct argumentation increases up to 76%
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Mixture Before instruction
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Mixture
- Natural origin prevails over visual assessment
Before instruction
3. RESULTS AND DISCUSSION 3. Classify these products as “pure substance” or “mixture”
3. Classify these products as “pure substance” or “mixture”
Mixture
- Olive oil a weak increase
After instruction
Analysing justifications question 3:
MIXTURES: JUSTIFICATIONS
MIXTURES: JUSTIFICATIONS
Before instruction: Students referred to manufactured origin “They are processed substances” ; “It is artificial” (to justify copper, silver and iron like mixtures)
Analysing justifications question 3:
MIXTURES: ARGUMENTATION
MIXTURES: ARGUMENTATION
Before instruction: “They are processed substances” ; “It is artificial” (to justify copper, silver and iron like mixtures) After instruction: correct justification increased to 85%
CONCLUSIONS
Students don’t difference between a pure substance and a mixture, especially if the mixture is a natural product like cow milk
Students have a restricted conception of mixture that is specially focused on what they perceive. They excluded products that are naturally mixed, including heterogeneous samples like granite stone or sand
Also, students associate "mixture" with "processed product“ like iron, salt, silver or copper
Overcoming the above mentioned alternative conceptions is possible after an appropriate instruction.
It is important to note that this change must be addressed in Primary Education because these ideas persist and are shaped as mental structures that impede scientific learning.
References Martín del Pozo, R. y Galán Martín, P. 2012. Los criterios de clasificación de la materia inerte en la Educación Primaria: concepciones de los alumnos y niveles de competencia. Revista Eureka sobre Enseñanza y Divulgación de las Ciencias, 9:213-230. Martínez Losada, C., García Barros, S., Rivadulla López, J.C. 2009. What students of primary and secondary know about material systems? How to treat it in textbooks? Revista Electrónica de Enseñanza de las Ciencias, 8: 137-155.
GRAZIE
International Workshop
“SCIENCE EDUCATION AND GUIDANCE IN SCHOOLS:
THE WAY FORWARD”
Firenze, 21-22 October, 2013