Abstract:

The project named "Chemical Reaction" is presented. It contains the following three teaching sequences: “From materials, to mixtures and substances”; “What changes and formations occur during a chemical reaction?”; and “Application of the chemical reaction to residual water treatment”. The objective of its structure is to allow for young students to participate in activities destined to develop scientific competition through the use of small scale materials recreating a mini-laboratory.

The experimental experiences are not only attractive, but they also motivate and arise interest in students; the activities also take place in familiar situations and with known material; at the same time, they are useful and easily achieved. The objective is to promote students interest in research, as well as to help them understand the point of Chemistry’s study.
The development of certain cognitive abilities is highlighted, such as comparison, classification, identification, arrangement, organization, prediction, interpretation, observation, description, explanation, justification, modeling, and argumentation. In addition, the participants will become familiarized with different types of chemical reactions; they will be able to macroscopically observe changes, and use the acquired knowledge to solve issues as relevant as water contamination and residual water treatment, which incites reflection upon the care for the environment and the advantages of collaborative work.
The conceptual, procedural, and actitudinal knowledge involved are part of the “2011 Junior High School Study Programs of the Secretariat of Public Education in Mexico.

Several authors, such as Spencer (1992), Gillespie (1997), Garritz (1998), Camaño (2003), and Atkins (2005), agree on the fact that the concept of chemical reaction is of vital importance to the teaching of chemistry, from a middle to a higher educational level (Reyes, 2006). However, it is a difficult subject for junior highschool and highschool students to grasp. According to these authors, the difficulty comes from the student’s low capability to go from the representation of a macroscopic reaction to a microscopic one, and then to its symbols and formulae (Balocchi, 2005).

In 1996 and 2004, Johanson, Azcona, and Kind, suggested the need to begin the study of chemical reactions parting from the definition of substance, suggesting that a collection of phenomenon must be presented within a focus that stimulates observation, questioning, and argumentation. They also propose for the atomic description to be imparted until students perceive the need of a general explanation in different terms than what they already manage. Because of this, the project begins with the definition of substance and the difference between this and the definition of mixture, and continues with the study of chemical reactions at a macroscopic level. The proposed sequence partially follows the Vos and Verdonk strategy (1985, 1986, and 1987) in order to introduce the subject of chemical reactions.

Keywords:

Chemical Reaction Didactic, Improving Scientific Competence in Junior High School Students.