Subject Area: VCE Chemistry
Author: Tina Tirabassi, Jarrod Bye, Nguyen Tran, Shekhar Shastri
This task is a practical investigation where students analyse a sample of unknown concentration of sodium hydroxide, determining the concentration of the solution using volumetric analysis techniques. Students conduct the practical, and then complete a formal scientific report.
The report will be used to complete the assessment, and will be marked against Bloom’s and Dreyfus’ taxonomies. Students will follow the conventional format of a scientific report, as well complete a series of scaffolded calculations and discussion questions posing hypothetical scenarios and how they may affect the outcome of the investigation.
|Sub-domain||Unit 2 – What makes water such a unique chemical?|
|Strand||Area of Study 2 – How are substances in water measured and analysed?||Substrand||Outcome 2 – Analysis of acids and bases in water|
|Purpose||The purpose of this task is to surmise student ability to determine the concentration of sodium hydroxide by performing a volumetric analysis using titration and stoichiometry, Student ability to write a formal science report and evaluate data using scientific knowledge and understanding. Key science skills to formulate aims and hypotheses, conduct experiments, record results and discuss results in relation to hypotheses will also be assessed. Assessment of scientific communication is also a key component of the task.
As a formal practical report, this task will enable appropriate assessment of both key science skills and student understanding of curriculum outcomes.
|Administer||The assessment will span over three fifty minute periods. A double period to conduct the experiment, and a single period to complete the formal practical report. Students work in practical groups to conduct the experimental aspect of the assessment. Once data is recorded, students individually complete a practical report making this an authentic assessment as students complete this on their own during a supervised lesson without collaboration and input from peers. All scientific equipment and chemicals will be provided to students, as well as a handout which outlines procedures and questions. Students are allowed access to any additional resource helpful to completing the report, and only ask for assistance during the practical component.|
|Records||Marks from the assessment will be retained in the teacher’s markbook, and will contribute to end of year results. As students were required to write the practical report individually under test conditions, the task will provide authentic data that reflects student understanding of concepts. Being a knowledge-based application task, noise will also be limited as students cannot complete it with guess work, furthering the authenticity of the task, as well as providing an accurate representation of student ability.|
|Interpret||Based on their performance in the practical and the quality of their report, the teacher determines student understanding of the volumetric analysis, application of stoichiometric techniques, and proficiency in key science skills.
As content knowledge needed to conduct the investigation are modelled in lessons prior to the investigation, and students have had the chance to practice skills needed for this summative assessment through chapter questions and worksheets, this task is adequate in assessing student understanding.
|Use||Students results are compared using Guttmann Analysis to determine areas the students need help with before moving on to more difficult volumetric analysis. Feedback is provided to students in the form of their assessment matrices, and written feedback stating what they can do and what they are ready to learn.|
|Outstanding||Able to correctly structure a scientific report, critically evaluate and engage in scientific concepts making clear links to chemistry theory and perform accurate stoichiometric calculations.|
|High||Demonstration of scientific understanding by making clear links to chemistry theory and the correct use of scientific terminology.|
|Medium||Be able to process the data and explain the data in the practical report. The report is organized following a science standard format.|
|Low||Be able to follow the procedure to complete a practical report.|
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