Chang, Chew Hung

The urban heat island phenomenon was examined at three spatial scales in this study. At the island-wide scale, the existence of the nocturnal heat island phenomenon at 2200 hrs for various "seasons" of the year in Singapore was confirmed. The study was undertaken at 2200 hrs to allow for comparison with an earlier study in 1981. The intensity of the phenomenon varies both spatially and temporary. The nocturnal phenomenon has changed since it was last studied in 1981. Secondary heat islands are now present over some sub-urban areas which were previously rural. Previous studies of Singapore's nocturnal heat island have recognised and described the phenomenon substantially but have failed to establish statistical relationship between factors and the phenomenon.

This study established some statistical correlation between some factors (such as urban canyon geometry and size of estate) and the nocturnal heat island phenomenon through empirical data examined at local scales. Urban canyon geometry, in terms of height-to-width ratios, and the physical size of the housing estates have positive correlations but the areal extent of waterbodies has negative correlations with heat island intensities. The role of canyon geometry in the processes involved in the genesis of the phenomenon was further examined at a micro-scale, where three canyons were studied for spatial and temporal variation in ambient temperatures, insolation and wind speed. Results show that canyons with higher height-to-width ratios tend to have weaker winds at the canyon floor and large spatial difference in ambient air temperatures between canyon floor and canyon top. Using the statistical results, a model to predict 2200 hrs heat island intensities based on urban canyon geometry, size of estate and areal extent of waterbodies was proposed. This model gives an overall p-value of 0.0002 with urban canyon geometry being the most statistically significant of the three parameters included in the model.

We often assume that when we engage a student in a constructivist learning activity on the internet, the student will be more motivated, learn more effectively and attain higher-order learning outcomes. However, little empirical research exists to confirm these assumptions. The central research question of this study was to explore what happens when a student is engaged in constructivist learning in a small group using resources from the web. Within the framework of an activity system, this study investigated how the student (subject) interacted with the web (tools) in the learning process (production) to generate the observed learning outcomes (object). This involved the views of teachers as stakeholders (community) and the way the students worked in a group (division of labour). Concepts from existing studies such as Borgman et al. (1990) and Kuhlthau’s (1993) study of information-seeking behaviour were used to explore some of these elements in the activity system conceptual framework. In essence, a Creswell (1998) and Guba and Lincoln (1989) adaptation of the Wolcott (1983) conception of a quasi-ethnography was used as the qualitative methodology for this study. In general, the results indicated that the students may be more motivated by assessment marks than the use of the internet. Students also felt that searching for information on the internet was frustrating, especially when information was in non-summarised and non-extracted forms and thus preferred to simply receive information from the teacher. The information-seeking behaviours noted were largely in the starting and chaining categories in Ellis’ (1995) terminology. Although some higher-order learning outcomes such as attitude and evaluation were present, the students were proficient with simply reproducing facts. The students also felt that working in a group was difficult which possibly indicated a lack of experience with working in groups. Time constraint to meet was a reason cited by the students that has hampered their learning together. The teachers also felt that such an activity was limited in its effectiveness and rather impractical as curriculum time is limited. Amidst the rather unpromising results arising from using the internet in this learning activity, the findings do provide useful information on how future constructivist learning activities, such as the use of WebQuests (Dodge, 1997), can be designed.