Les modèles et la modélisation de la réaction acide-base dans le ...

2. Methods, results and discussion
2.1. Research sampling and data collection methods
The investigation was carried out at the end of the 2006-2007 school year with 240
Congolese second-year chemistry students from ten secondary scientific schools of
DRC Bukavu region. We used a paper and pencil test. All the students were given the
same test (see Table 1). We wanted to learn more about whether students correctly
identify chemical and physical processes in order to comprehend chemical reaction
(CR) by giving a variety of slightly different interpretations and come to understand
different phenomena in order to handle CR. The null hypothesis was they could
distinguish the PP or CP and easily identify the CR using scientific criteria as attended
by the chemistry curriculum. Thus they would be able to transfer –as an important
objective of the chemistry curriculum- their class knowledge to everyday life
situations.
Number
Question
1 Establish the difference between chemical phenomena and physical phenomena
2 Define chemical reaction in your own terms and give two examples
3 Distinguish physical from chemical phenomena. Explain your answer and state in
which a chemical reaction occurs (see the list of nine phenomena learnt in class)
4 Cite the different categories of reaction you know (learning class)
5 Give 20 natural phenomena (everyday experiences), say which can be qualified as
chemical phenomena. Specify in which case a chemical reaction occurs (do not cite
any example similar to question 3 examples).
Table1. Questionnaire tested
[NB: there follows a list of nine assumptions concerning: (a)burning paper (b)sawing
wood (c)rusting (d)ripping up clothes (e) varnishing nails (f) shaving (g) cooking food
(h)producing beer (i)synthesis of an indicator]. These are the main examples taught
at school and might have some applications in the nature.
Our test was composed of five questions: the first question Q1 to fourth question Q4
for school knowledge and the fifth question Q5 for everyday life situations. We
wanted pupils to establish the difference between PP and CP (Q1), to define the
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