Why go organic? Share that your soil is full of critters, many of which contribute to the perfect nitrogen balance of your soil. Teach up-to- date information about the soil food web. Worms are now considered biological indicators of soil. Read on...
In addition to teaching, I have been developing how to teach teachers/homeowners how to do worm composting inside successfully for years at www.wormwatcher.com via email support. See our store at TheGREENInventor on this site.
Plants are in charge of creating the perfect amount of nitrogen they need in their soil. How? By sweating chemicals (exudates) to attract the bacteria/fungi that do the work of creating the nitrates/nitrites that the plants need.
SO think about what happens when we add strong fertilizers or chemicals to soil in our yard? This is why composting and compost/worm tea is now so popular. It's not for drinking; it rebuilds your soil. Here's some ideas to teach this concept to any grade level. I just shared it to preschoolers at a local Montessorri - THEY GET IT..