Lian‐Sai Chia

The main objective of this paper is to review recent advances in plant drug research and developments in orchid study, in an attempt to provide useful references for plant drug studies. Plants have been used as medicine for millennia. Out of estimated 250 000 to 350 000 plant species identified so far, about 35 000 are used worldwide for medicinal purposes. It has been confirmed by WHO that herbal medicines serve the health needs of about 80 percent of the world's population; especially for millions of people in the vast rural areas of developing countries. Meanwhile, consumers in developed countries are becoming disillusioned with modern healthcare and are seeking alternatives. The recent resurgence of plant remedies results from several factors: 1) the effectiveness of plant medicines; 2) the side effect of most modern drugs; and 3) the development of science and technology. It has been estimated that in the mid-1990s over 200 companies and research organizations worldwide are screening plant and animal compounds for medicinal properties. Actually, several important drugs used in modern medicine have come from medicinal plant studies, eg, taxol/paclitaxel, vinblastine, vincristine, topotecan, irinotecan, etoposide, teniposide, etc. As for drugs derived from orchids, some novel discoveries, both in phytochemical and pharmacological properties, were reported by some universities. However, studies on plants are very limited. Only about a third of the million or so species of higher plants have been identified and named by scientists. Of those named, only a tiny fraction has been studied. Nowadays the linking of the indigenous knowledge of medicinal plants to modern research activities provides a new approach, which makes the rate of discovery of drugs much more effective than with random collection.

This is a revisited study on the role of cognitive variables, viz., concept relatedness, idea association, problem translating skill, prior problem solving experience, specific knowledge, and relevant but nonspecific knowledge in problem solving performance in chemistry. Two hundred seventy-nine preuniversity chemistry students from six Singapore junior colleges were involved in this study. This article presents results from the current Singaporean and the previous Australian studies on the relationships between the cognitive variables and problem solving performance in three electrochemistry problems of different degrees of familiarity for comparisons. The two studies confirm that the aforementioned cognitive variables, except concept relatedness, are significant determining variables of problem solving performance. Idea association and problem translating skill are the more important predictors for solving the familiar problem. The five cognitive variables, idea association, problem translating skill, prior problem solving experience, specific knowledge, and relevant but nonspecific knowledge, are all significant predictors of problem solving performance on solving the partially familiar problem. Among them, idea association is the most influential predictor. Problem translating skill is a significant predictor for unfamiliar problems. © 1996 John Wiley & Sons, Inc.

This work is an extension of the two previous studies which aims at verifying the importance of the cognitive variables to problem solving in Chemistry across topics and levels. The previous studies show that the five cognitive variables namely, Specific Knowledge, Non-Specific but Relevant Knowledge, Concept Relatedness, Idea Association and Problem Translating Skill, are the important predictors of problem-solving performance in the topic of Grade 12 Electrochemistry. This present study involved 115 Grade 9 Chemistry students, aged between 13 and 16, solving Mole Concept problems with the familiarity levels ranging from familiar to partially familiar. Four of the five cognitive variables, Specific Knowledge, Concept Relatedness, Idea Association and Problem Translating Skill, have been found to be significant in predicting problem-solving performance with Idea Association being the most significant. The study also suggests that the difference in the topics and levels appeared to have little effect on the importance of these variables on problem-solving performance. [Chem. Educ. Res. Pract. Eur.: 2001, 2, 285-301]

The purpose of this study was to investigate the extent to which science teachers taught problem solving in elementary science. The survey involved 348 teachers in 36 Singapore elementary schools. The study investigated the science teachers’ views about their use of science instructional techniques in general and the problem-solving teaching approach in particular. It also focused on the difficulties faced by science teachers in implementing the problem-solving teaching approach in the science classroom. It was found that the most emphasised activities were completion of science workbooks, teachers’ explanation of concepts, and hands-on activities. The least emphasised activities were computer-based learning, activities beyond the textbook and workbook, and visits to the ecology garden and other parts of the school. Only about one-third of the teachers often conducted activities pertaining to problem solving. Most of them were more concerned about covering the science syllabus for examinations, the physical constraints of the learning environment, and pupils’ abilities and motivation. On the other hand, teacher-related factors ranked low: these included teachers’ preference for teaching and learning outcomes, their ability to maintain control over pupils’ learning, feelings of inadequacy of science knowledge, and insufficient understanding of the pedagogical method of teaching problem solving.