Appropriate for Grades 9-12 Students will use a PASPORT dissolved oxygen sensor to examine the effect of 3 common types of water pollution--thermal, biodegradable and chemical--on dissolved oxygen levels. This activity can be completed in one 50-minute lab session. Includes 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.