Explain how artificial fertilisers, pesticides and the destruction of hedgerows affect wildlife.
Give each girl a napkin/serviette & a chocolate chip cookie plus a tooth pic.
Brownies should pic out and eat all the chocolate chips.
Then read to them The Lorax by Dr Seuss
Then Brownies should try to put the cookie back together exactly the way it was when they were given it.
See if they can see how the cookie is like the habitat, when you take-away part of the habitat it can never be the same again no matter how hard you try.
Then let them eat the rest of the cookie.
It doesnt really take into account the fertiliser but does show the destruction fo the hedgerows.