1. International Workshop
“SCIENCE EDUCATION AND GUIDANCE IN SCHOOLS:
THE WAY FORWARD”
Firenze, 21-22 October, 2013
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

2. Summary
 1. Introduction
 Alternative conceptions
 Alternative conceptions reports on material systems at
Primary education
 Work goals
 2. Methodology
 3. Results and discussion
 4. Conclusions

3. 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

4. 1. INTRODUCTION
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
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.

5. 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

6. 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
These conceptions lead to conceptual mistakes
and are an obstacle in learning scientifically
correct concepts
They must be considered during the educational
process to ease significant learning

7. Alternative conceptions reports on material systems at
Primary education
Confusion between pure substance and
homogeneous mixture
Martínez Losada et al.
(2009)
Pure substance is identified with natural
origin
Students match mixture with processed
material
Natural origin prevails over perception
Martín del Pozo, Galán Martín
(2012)

8. Work goals
1.
2.
Identify alternative conceptions of students in the third stage of
Primary Education on material systems (pure substances and
mixtures)
Design teaching tools to overcome of alternative conceptions

9. 2. METHODOLOGY
RESEARCH METHOD
DESCRIPTIVE AND
INTERPRETATIVE
METHODOLOGY
SAMPLE SELECTION
21 STUDENTS 5TH PRIMARY
EDUCATION (Age: 10 – 11
years)
DATA INTSTRUMENT
QUESTIONNAIRE

10. 2. METHODOLOGY
RESEARCH METHOD
DESCRIPTIVE AND
INTERPRETATIVE
METHODOLOGY
SAMPLE SELECTION
21 STUDENTS 5TH PRIMARY
EDUCATION (Age: 10 – 11
years)
DATA INTSTRUMENT
QUESTIONNAIRE
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)

11. 2. METHODOLOGY
DEVELOPMENT
4 WEEKS
1st, 2nd week  Students completed questionnaire
in the class
 Detection of alternative conceptions
 Planning instruction in basis of the
results

12. 2. METHODOLOGY
DEVELOPMENT
4 WEEKS
3rd week
2 Session class

13. 2. METHODOLOGY
Theorical (1 h)
Practice (1 h)
PowerPoint
Explanation of
key concepts
Taking into account
Pre-test results
students-teacher
Interaction
Students’ textbook

14. 2. METHODOLOGY
Theorical (1 h)
Practice (1 h)
PowerPoint
Chemistry workshop
Explanation of
key concepts
Taking into account
Pre-test results
students-teacher
Interaction
Students’ textbook
Implementation of
the acquired
knowledge
Cooperative work

15. Practice phase
Cooperative work
Groups of 4-5 students
Group notebook
Activities
Classify
Pure substance/mixture
Mix
Homogeneous/heterogeneous
Experiment
milk

18. 2. METHODOLOGY
DEVELOPMENT
4 WEEKS
4th week

19. 3. RESULTS AND DISCUSSION
1. Mixing water and oil: homogeneous or heterogeneous?
*

20. 3. RESULTS AND DISCUSSION
1. Mixing water and oil: homogeneous or heterogeneous?
25%
*

21. 3. RESULTS AND DISCUSSION
1. Mixing water and oil: homogeneous or heterogeneous?
AFTER INSTRUCTION
95%
*

22. Analysing justifications question 1:
STUDENTS SELECTING HOMOGENEOUS: JUSTIFICATIONS
Before instruction: “Incorrect classification, correct justification”
Students know substances remain separate but
don’t match with correct criterion

23. Analysing justifications question 1:
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
*
Before instruction: Just one student gave the correct argumentation

24. Analysing justifications question 1:
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
*
Before instruction: Just one student gave the correct argumentation
After instruction : correct argumentation increases up to 40%

25. Analysing justifications question 1:
STUDENTS SELECTING HETEROGENEOUS: JUSTIFICATIONS
*
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

26. 3. RESULTS AND DISCUSSION
2. Milk is: a pure substance or a mixture?
*

27. 3. RESULTS AND DISCUSSION
2. Milk is: a pure substance or a mixture?
14%
*

28. 3. RESULTS AND DISCUSSION
AFTER INSTRUCTION
2. Milk is: a pure substance or a mixture?
66%
*

29. Analysing justifications question 2:
STUDENTS SELECTING PURE SUBSTANCE: JUSTIFICATIONS
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

30. Analysing justifications question 2:
STUDENTS SELECTING MIXTURE: JUSTIFICATIONS
*
Before instruction, nobody gave a correct argumentations
After instruction “Milk is a mixture because is formed by several
components”

31. 3. RESULTS AND DISCUSSION
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…

32. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
Before instruction
Pure substance

33. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
Before instruction
- Materials used in a
processed way
Pure substance

34. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
After instruction
Pure substance

35. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
After instruction
Pure substance

36. Analysing justifications question 3:
PURE SUBSTANCES: JUSTIFICATIONS
*
Before instruction, the origin (natural or manufactured) notion remains
versus composition

37. Analysing justifications question 3:
PURE SUBSTANCES: ARGUMENTATION
*
Before instruction, the origin (natural or manufactured) notion remains
versus composition
After instruction, correct argumentation increases up to 76%

38. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
Before instruction
Mixture

39. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
Before instruction
- Natural origin prevails
over visual assessment
Mixture

40. 3. RESULTS AND DISCUSSION
3. Classify these products as “pure substance” or “mixture”
After instruction
- Olive oil a weak increase
Mixture

41. Analysing justifications question 3:
MIXTURES: JUSTIFICATIONS
Before instruction: Students referred to manufactured origin
“They are processed substances” ; “It is artificial”
(to justify copper, silver and iron like mixtures)

42. Analysing justifications question 3:
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%

43. 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.

44. 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, 9:213230.
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.

45. International Workshop
“SCIENCE EDUCATION AND GUIDANCE IN SCHOOLS:
THE WAY FORWARD”
Firenze, 21-22 October, 2013
GRAZIE