Lee, Yew-Jin

A questionnaire survey was administered to 66 secondary 5 Normal level students in Singapore to sample students' ideas on the scientific concept of food in school biology. Between 30% to 60% of the respondents believed that food yielded energy but this concept was context dependent and not widespread. Primary responses predominated as students felt that the biological functions of food were for sustenance, satiation, growth and general well-being. They seemed to hold a simplistic view that anything that was consumable (edible) was considered to be a food. More than 75% of the sample accepted the idea that food can be in liquid state. Students' understanding of the biological concept of food was anthropocentric and not applied across living organisms in heterotrophs (animals) or autotrophs (plants) as a whole. The components of a balanced diet were understood but many students confused the concepts of nutrients and water, believing the latter to be a food.

According to research studies, the topic of biological evolution proved to be extremely difficult to teach and to learn in schools. One possible reason for this situation was the lack of subject matter knowledge competence in this topic by biology teachers. Indeed, competence in subject matter knowledge (SMK) has been shown to be a central feature of the teaching profession. This study had hoped to determine the level of comprehension of biological evolution by Singapore high school biology teachers in which there is a dearth of information at the local level. Results of this study has important implications for teaching and learning evolution, teacher education and re-education.

A five option multiple-choice questionnaire with 24 questions on evolution and 12 on ecology was devised to ascertain the teachers' levels of comprehension in biological evolution. The results of the ability scores from a total of 52 teachers ranged from 3.53 to -0.56 logits (M=1.12 logits,SD=0.97); that of senior high or junior college (JC) teachers (n=12) ranged from 3.53 to 0.33 logits, and for junior high or secondary teachers (n=40) from3.01 to -0.56 logits (M=0.89 logits, SD=0.86). Mean total score in the achievement test for JC (M=79.4% or 1.86 logits, SD=1.0) and secondary school teachers (M=66.6% or 0.89 logits, SD=0.9) were significantly higher in favour of JC teachers (p<0.005). Similarly, JC teacher scores over the sub-section of evolution were significantly higher (p<0.001) than secondary teachers but not so with respect to ecology items. Lower ability teachers (mainly secondary school teachers) seemed also to experience greater difficulty with questions pertaining to evolution rather than on ecology.

Secondary school and JC teachers were found to be quite alike in terms of background variables like age, gender, teaching experience, number of years since graduation, religious affiliation, membership of professional organisations, academic qualifications, and past educational experience in evolution and ecology. JC teachers seemed to have a significantly greater number of years (p<0.05) of teaching pure biology compared to secondary teachers. Negative correlation existed between years of teaching pure biology in JC teachers and performance in the achievement test although there was moderate positive correlation between these variables among the secondary teachers. About 60% of JC teachers felt that they had mastered ecology and evolution in their present teaching job while the majority of secondary teachers indicated mastery at the time when they studied at the university. Analysis of achievement test scores from a sample of 24 pre-service student teachers supported the possibility that teaching and learning on-the-job as biology specialists in the academically demanding college environment contributed to higher scores in the achievement test for JC teachers. This had translated into significantly greater (p<0.005) actual coverage and emphasis given to evolution by JC teachers than by secondary school teachers. Similarly, the intended coverage and emphasis by JC teachers were significantly more (p<0.05) than that of secondary teachers.

Analysis of the achievement test results revealed specific instances of misconceptions or alternative conceptions. These inappropriate concepts were more often spotted amongst the answers by the secondary teachers than the JC ones. The alternative conceptions included three main key concepts, namely;

The Theory of Evolution in General, Speciation, and Natural Selection which are discussed in detail in this study.