Examine the effects of common pollutants on an organism that is abundant in all aquatic environments-algae! Simulated fertilizer run-off containing nitrates and phosphates is added to locally collected algae-rich pond water or to purchased algae cultures. The amount of growth is compared against control samples without adding nutrients. Students also examine the algal cells using a microscope and record cell counts. After completion of this activity, students will understand how fertilizer run-off leads to algae blooms and why nitrate and phosphate pollution is an important environmental concern. Enough materials provided for a class of 30 students working in pairs.