CHAPTER ONE

1.1 Background

Chemistry is one of the most important subject in science and therefore it is offered in the Nigerian secondary school curriculum. A credit pass in the senior secondary certificate examination is required to get admission into almost all basic and applied science discipline in tertiary institutions.

Research has shown that Nigerian students persistently perform poorly in chemistry owing to poor problem- solving in stoichiometry (Opara, 2013; Udosoro, 2011; Badru, 2004). West African Examinations Council (WAEC) Chief Examiners, perennially report on students’ weaknesses in chemical arithmetic, poor mathematical skills and inability to determine mole ratio from stoichiometric equations (2007 – 2017). The field of stoichiometry involves all forms of measurements and the calculations that relate to each other. Stoichiometry is at the heart of chemistry since it refers to the relationship between the measured quantities in a chemical reaction as well as the calculation which include the assumption of the laws of definite proportions and of the conservation of matter and energy. Stoichiometry requires that the number of atoms or molecules involved in chemical reaction be converted into measured quantities expressible in convenient units. Parker (1983) proposed four groups that constitute the principle of stoichiometry. 
They are:

·        The law of conservation of matter

·        The law of chemical combining weights

·        The law of combining proportions

·        The rates of reaction relationships in a system. 

Calculations involving these principles are of great significance in engineering practice and existing operations or designing new manufacturing particles and equipment. A solid foundation in stoichiometry is necessary for understanding quantitative deductions in physical chemistry. 

Despite the relevance of stoichiometry in physical chemistry studies have shown that learners find stoichiometric calculations difficult (Evans, Yaron and Leinhardt, 2008; Fach, de Boer and Parchmann, 2007 and Furio, Azconu and Guisasola, 2002). Evidence of students’ misconceptions and understanding of stoichiometry exists in literature (Gauchon and Meheut, 2007; Arasasington, Taagepera and Potter 2004). Other researches attempted to develop problem-solving models and instructional strategies to foster students’ success in stoichiometry (Chandrasegran, Treagust, Waldrip and Chandrasegaran, 2009). There is a clear relationship between students’ proficiency in mathematics and their understanding of chemical arithmetic (Badru, 2004). Thus, it is essential to create anxiety-free environment within a social, democratic field where learners can fully participate in the learning process and engage one another’s intellectual, academic and social aptitudes. 

Within the last decades, observation has shown that in spite of the various innovations introduced into science teaching in general and chemistry in particular, the performance of students still remains low. This is buttressed by the poor performance of students in West African Senior Secondary Certificate Examination (WASSCE).

Problem solving is an application of previously acquired knowledge and skills to achieve certain goals. Various definitions of problem-solving abound in the literature. Every researcher and author defines it in terms of his/her own psychological orientations. Krulik and Rudnick (as cited in Carson, 2007) defined problem solving as the means by which a person uses previously acquired knowledge, skills, and understanding to satisfy the demands of an unfamiliar situation. The student must synthesize what he or she has learned, and apply it to a new and different situation.

Behaviorists view it in terms of association between the problem situations and ideas or objects that may have the greatest potentials for providing the correct solutions. The solution to a problem is seen as a matter of scanning and association; connecting chains of conditioned responses; turning up the right association or searching for the responses that can be associated with the problematic situation. It is described as reproductive thinking such as drill and practice; trial and error. Gestaltist view problem solving as an insightful or intuitive process involving the perceptual processes of the solver. Cognitivists view problem-solving in terms of information processing involving internal mediating factors and refer it to the mental process that people go through to discover, analyze and solve problems. This involves the entire discovery of the problems, the decision to tackle the issue, and understanding the problem itself.

If the understanding of the problem is faulty, the attempts to resolve it  will also be incorrect or flawed. It is a type of discovery learning, whose emergence depends on the structure of the task, and may be independent of the solver’s prior knowledge. It largely depends on the solver’s ability to discover general procedures for solving problems of particular kinds through certain manipulations at times involving a period of fumbling and search, and of the emergence of correct hypotheses. In this case, the problem-solving is reflective of a process of progressive clarification of means-ends relationships in which formulations, testing and rejection of alternative hypotheses plays a leading role. 

Carson (2007) stated three characteristics of problem solving as

1.     connecting theory and practice.

2.      Problem-solving teaches creativity.

3.      It also teaches transfer and application of conceptual knowledge.

Villegas, Castro and Guterrez (as cited in Mushtaq, 2010) also stated two characteristics of problem-solving as

1.      providing opportunity for practicing heuristics as a valuable procedure producing added motivation due to their potential for application and

2.     Providing creativity required in using multiple mental representations.

Problem solving is also very important to students. It can also be said that problem-solving is like a fun game, it stimulates the students and makes them enthusiastic. It makes the process of teaching and learning lively. Problem solving provides students with the chance to solidify and extend their knowledge and also stimulate new learning (Akinsola, 2008). Problem-solving can be concluded to be part of classroom instruction as well-developed problem-solving skills are important for a wide variety of reasons. First, they are important for real life. Every day both adults and children

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