This study provides a definition of scientific literacy applicable to secondary school science students. The definition was developed from theories about cognitive processes, the discourse of science, the language register of science and cognitive writing processes. A computer-assisted Scientific Literacy Development Plan was formulated and classroom research undertaken to test its effectiveness. A model of cognitive writing was used as an application of the Scientific Literacy Development Plan in classroom research. The model is called a HyperCard Pathways writing model.The research methodology was a combination of qualitative and quantitative methods and took place in three phases over three academic school years. The HyperCard Pathways model of writing was developed in modules for the topics of the Year 11 Physics Extended Subject Framework of the Senior Secondary Assessment Board of South Australia. Students used the modules for the completion of required pieces of writing in science as part of the requirements for the South Australian Certificate of Education. Results indicated that the Scientific Literacy Development Plan was an effective tool for the enhancement of scientific literacy of Year 11 physics students and there was potential for the use of the plan in other science subjects. A number of teachers incorporated the techniques of the Scientific Literacy Development Plan into their regular course schedules.In conjunction with the classroom research, a method to assess explanation genre essays was developed called the Scientific Explanation Genre Assessment Scheme. This was trialled independently of the trials of the Scientific Literacy Development Plan and was found to be used reliably by teachers of Year 11 physics. The effectiveness of the computer-assisted Scientific Literacy Development Plan was demonstrated by evidence of improvement in scientific ++ / writing beyond that of normal practice. The products of this research: lesson plans, computer discs, and supporting materials were developed to be of assistance to other teachers. The materials can be adapted to other modules in the science curricula, and, following this project some teachers have chosen to do this.

PlantingScience (PS) is a unique web-based learning system designed to develop secondary students' scientific practices and proficiencies as they engage in hands-on classroom investigations while being mentored online by a scientist. Some students' teachers had the opportunity to attend PS professional development (PD). In this dissertation, I developed a process of assessing student learning outcomes associated with their use of this system and evaluated inquiry engagement within this system. First, I developed a valid and reliable instrument (Online Elements of Inquiry Checklist; OEIC) to measure participants' (students, scientists, and teachers) engagement in scientific practices and proficiencies embedded within an inquiry cycle I collaborated with an expert-group to establish the OEIC's construct and content validities. An inter-rater reliability coefficient of 0.92 was established by scientists and a split half analysis was used to determine the instruments' internal consistency (Spearman-Brown coefficient of 0.96). Next, I used the OEIC to evaluate inquiry cycle engagement by the participants who used the PS online platform designed by the Botanical Society of America which facilitated communication between participants. Students provided more evidence of engagement in the earlier phases of an inquiry cycle. Scientists showed a similar trend but emphasized experimental design and procedures. Teachers rarely engaged online. Exemplary students' outcomes followed similar inquiry cycle trends, but with more evidence of engagement with one notable difference. Exemplary students provided evidence for extensive engagement in immersion activities, implicating immersion as a crucial component of successful inquiry cycle engagement. I also compared engagement outcomes of students whose teachers attended the PD experience to the students of teachers who did not attend PD. Differences found between the two groups occurred throughout the inquiry cycle, typically associated with experiences provided during the PD. As a result of this research I have several recommendations about revisions to the PS online platform and use of approaches to assure students development of scientific practices and proficiencies. The recommendations include additional scaffolding of the platform, explicit inquiry cycle instruction, and continued opportunities for teachers to engage in PD experiences provided by PS.