1. Air Pollution & Traffic in Hanoi | Investigating vehicle count trends towards the CBD, measuring air quality index, and analyzing pollution correlation. 2. Data Collection & Graphical Analysis | Conducting fieldwork, using tally methods, plotting vehicle counts and air pollution data on graphs. 3. Infiltration & Soil Moisture Study | Measuring infiltration rates at different sites, comparing soil moisture content, and assessing terrain slope effects. 4. Drainage Basin & Environmental Factors | Evaluating factors influencing infiltration, analyzing vegetation impact, and human activity effects on soil permeability. 5. Experimental Design & Accuracy | Using secondary sources, justifying sampling methods, and improving reliability through controlled variables. 6. Fieldwork Extensions & Survey Techniques | Applying bipolar surveys for environmental quality assessment, integrating observational data, and refining methodologies for accuracy.