Students will use a PASPORT pH sensor to measure the acidity or alkalinity of community soil samples, employing real-world standard test procedures used by soil scientists and environmental researchers. This activity can be completed in 2 50-minute lab sessions. Grades 9–12. Includes materials for 30 students and instructions. Requires 1 sensor, plus 1 USB Link or 1 Xplorer Datalogger, for each group of students. When you want to use more than one USB Link or Xplorer (or any combination), the USB 4-Port Hub expands your single USB to four USB ports.