National Standards for Grade Levels 9-14
 
Mechanisms of Herbicides was designed to demonstrate the effectiveness of different categories of herbicides. Students transplant grasses and weeds into flats or pots and investigate how and why different plants are killed by different chemicals. A simultaneous microbiological proof with inoculated agar plates is run to reinforce the results, further categorize herbicides, and determine potential effects of the herbicides on soil microorganisms. Each group will choose two natural products and design a simple experiment to compare chemical vs. natural weed killers. The experiments culminate in a round table discussion including experimental designs, results, comparisons, and environmental impact. Requires five class periods, plus research time. Required, but not included: heat source, flower pots or nursery flats, grass and weeds for transplanting. Designed for 24 students working in four groups of six.