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U n i v e r s i t y of P e r a d e n i y a

The Institutional Repository of the University of Peradeniya is the University's digital gateway to scholarly knowledge and research excellence. Established as the next phase of the Digital Library initiative launched by the University Library in 2011, it preserves, showcases, and provides open access to the intellectual output of the University community.

Through a rich collection of research articles, conference proceedings, theses, dissertations, and other scholarly works, the repository enhances the visibility, accessibility, and long-term preservation of knowledge, extending the global reach and impact of the University of Peradeniya’s academic and research contributions.

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Consistency of defocus estimation under pupil-size extrapolation of Zernike wavefront coefficients
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2026-09-24) Lakshmi, M. P. D. S.; Fernando, T. S. D.; Karunarathna, S. P. D. S. S. K.; de Silva, T. M. M.
Precise quantification of refractive defocus is essential to vision science and in the design of optical correction strategies based on wavefront sensing. Zernike polynomials are widely used to represent ocular aberrations, and extrapolation of Zernike coefficients across different pupil sizes is often carried out without adequate assessment of their physical validity, since the corrections are made over the largest pupil size. Unlike prior works, we therefore analytically evaluated the stability of defocus estimation under pupil-size extrapolation. To this end, the refractive defocus values were varied to correspond to refractive errors ranging from 0 to -5 D at a reference pupil radius of 1.5 mm. The resulting wavefronts were extrapolated to larger pupils with radii ranging from 1.75 to 3. 00 mm. The defocus-equivalent (DE) values were then evaluated using the standard Zernike-based conversion. The distribution of DE values shows a linear trend at each pupil radius, with slopes that gradually flatten as pupil size increases. Numerically, the normalized slope decreased from 1.00 at 1.5 mm to 0.54, 0.32, 0.20, 0.13, 0.08, and 0.06 at 1.75, 2.00, 2.25, 2.50, 2.75, and 3.00 mm, respectively. For the first 0.25 mm increase in pupil radius, the results show a reduction of DE of almost 50%. Therefore, for larger pupils, defocus extrapolation across pupil sizes is mathematically ill-conditioned, potentially leading to biased or non-physical estimates. These findings highlighted a critical limitation of Zernike-based methods and emphasized the need for physically consistent, pupil-independent frameworks for precise measurement and correction of refractive error.
The effects of parental involvement on the academic achievement of senior secondary students: a case study from the Kalmunai education zone, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2026-09-24) Santharupan, V.; Anandhacumarasamy, S.; Dewasurendra, M. T. M.; Chathuranga, K. M. N. M.
Parental involvement is widely recognized as a key determinant of student achievement. However, evidence from peripheral, socio-economically disadvantaged regions of Sri Lanka remains limited. This study investigates the effects of parental involvement on the academic achievement of senior secondary (Grades 10–11) students in the Kalmunai Education Zone, Ampara District, Eastern Province, Sri Lanka. Adopting a mixed methods design, data were collected from 60 teachers, 120 students, and 120 parents using questionnaires, and from 47 educational stakeholders, including principals, deputy and assistant principals, zonal education officers, and school development society members, through semi-structured interviews, direct observation, and document reviews across twelve schools. Quantitative data were analyzed descriptively, while qualitative data were analyzed thematically and triangulated with quantitative findings. The findings show that parents’ educational level, economic status, time allocation, and direct educational support are associated with student achievement. The majority of teachers regarded parental involvement as highly important (42 of 60, 70%), while a substantial proportion of parents allocated only limited time to their children’s studies (61 of 118, 52%) and reported average or low economic status (82 of 120, 68%). The principal challenges constraining involvement were parents’ time constraints, low educational qualifications, and economic hardship. Thematic analysis of interviews and survey data revealed that active parental support, academic interest, and constructive parent–teacher collaboration were key facilitators of improved achievement, whereas educational, economic, and time-related limitations were consistently cited as negative influences. The study recommends that strengthening parent-teacher partnerships, together with targeted parental education, economic support, and awareness programs, is essential for improving student achievement in disadvantaged zones. As the first focused investigation of parental involvement in the Kalmunai Education Zone, it offers context-specific guidelines for educational planners, school administrators, and policymakers.
Learning science in bilingual mode: trends and issues in Monaragala district
(University of Peradeniya, Sri Lanka, 2019-10-11) Kumara, G.R.S.P.; Yatigammana Ekanayake, T.M.S.S.K.
The aim of this research was to explore the trends and issues of teaching and learning of science as a bilingual subject in schools in Monaragala district. Specific objectives were to explore the present status of learning science in bilingual mode (BM), to investigate the student’s perception toward learning science, to identify problems teachers encountered in teaching in BM and to find out suggestions to enhance teaching and learning science in BM. This is a mixed methods study and used the concurrent triangular design. The sample consisted of purposively selected 120 students from six schools in Monaragala and one science teacher from each school. A data sheet, and a questionnaire were used to collect quantitative data and an interview was conducted with teachers to collect qualitative data. Quantitative data were analyzed using MS Excel and qualitative data were analyzed using thematic analysis technique. According to the findings, in Monaragala only 9 schools offered bilingual education in 2010 and it has been increased to 19 by 2017. The number of students following science in BM increased from 900 (in 2010) to 2320 (2017). The percentage of passing rate of science in O/L examination were 95%, 88%, 96%, 100%, 93%, 97% and 92% respectively from the year 2010 to 2016 and it was 100% in 2017.According G.C.E.O/L results in 2017, there were 36% of “A” passes, 30% of “B” passes, 24% of “C” passes and 11% of “S” Passes and there was not any week passes. Quantitative results show that 114 students selected BM based on their choice, and they thought BM is important for their higher education and to improve English proficiency. Teachers thought teaching science in BM is a challenge; they satisfied about the school community support and provided suggestions to enhance BM in Monaragala district.
Challenges in implementing environmental sustainability education in junior secondary science education in Western Province, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2026-09-24) Liyanage, T. I. S. S.; Yatigammana, T. M. S. S. K.; de Silva, P. M. C. S.
Environmental Sustainability (ES) has become an important focus of education in response to growing global environmental concerns and the need to foster environmentally responsible behaviors among students. Science education provides an important context for integrating ES into school learning. Although sustainability themes are included in the Sri Lankan school science curriculum, limited attention has been given to the challenges teachers face in implementing ES-based teaching and learning. Therefore, this study examined teachers’ perceptions of the availability of institutional and professional support, and the barriers to effectively integrating ES into science pedagogy in the junior secondary classrooms. A quantitative descriptive survey design was used to collect and analyze data from 328 junior secondary science teachers in government schools in the Western Province. The findings identified several key barriers to integrating ES into science teaching. Only 13% (42) of participating teachers reported receiving training to promote ES through science pedagogy. Among the reported sources of training, 8 teachers identified national-level training, while 14, 17, and 9 teachers reported school-level, provincial-level, and private sector training, respectively. Moreover, 96% of teachers perceived parental involvement in promoting students’ ES competencies as poor. These findings highlight the need to expand access to ES-related teacher training, strengthen the quality and availability of professional development opportunities and institutional support, and enhance parental involvement in developing students’ ES competencies.
A study of the impact of GeoGebra software on teaching circular Geometric theorems in G.C.E. Ordinary Level classes in type 2 schools in the Polgahawela division, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2026-09-24) Senarathna, D.; Wijesooriya, U. D.
Geometry accounts for approximately one-quarter of the G.C.E. Ordinary Level (O/L) Mathematics examination in Sri Lanka, yet circular geometry remains challenging, with consistently poor performance in questions on circular theorems. This underachievement has been attributed to weak spatial-visualization skills, limited geometric reasoning, and traditional teacher-centered methods that emphasize memorization over conceptual understanding. GeoGebra, a free dynamic mathematics software, enables interactive exploration and visualization of geometric concepts, potentially enhancing conceptual learning. However, empirical evidence in the Sri Lankan context remains limited. This study investigated the impact of GeoGebra on teaching and learning circular geometric theorems among G.C.E. O/L students in Type 2 schools in the Polgahawela Division using a quasi-experimental mixed-methods design. A total of 62 students from two schools completed a pre-test (control M = 26.06, SD = 13.76; experimental M = 25.26, SD = 14.13) and were alternately assigned to the experimental and control groups based on pre-test rankings. Both groups improved, but the experimental group showed a greater mean gain (+16.71) than the control group (+6.55), with a higher post-test mean (M = 41.97, SD = 13.41) compared with the control group (M = 32.61, SD = 19.06). An independent-samples t-test confirmed a significant difference in post-test achievement (p = 0.029), with Cohen’s d ≈ 0.57 indicating a moderate effect. Post-intervention Likert-scale responses also showed higher engagement, confidence, perceived conceptual understanding, ability to identify angle relationships, and teacher–student connection among students taught using GeoGebra. These findings suggest that GeoGebra-based instruction was associated with greater achievement gains and more positive learning experiences. The study supports piloting GeoGebra through teacher training