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:floricanada@gmail.com

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