The student clearly states the independent variable, which is the volume of Copper (II) sulfate solution, and the dependent variable, the fermentation of lactic acid, in the research question. The methodology for analyzing these variables is well described, including the use of titration to measure the fermentation by the volume of NaOH required for neutralization. The student provides a comprehensive background theory section relevant to the investigation and explains the techniques used for measurement effectively. However, there is a lack of discussion regarding the choice of the number of trials and the precision of measurements, which should be addressed to strengthen the rationale. Overall, the student identifies and controls various variables while addressing safety, ethical, and environmental issues related to the investigation.
