We have previously shared the Four Commoner's Laws of Ecology (Barry Commoner, "The Closing Circle") and, while it isn't being applied in terms of an ecosystem application here, one of these laws can be used to help students better understand what this opportunity really means, too.

In microeconomic theory, the opportunity cost of a particular activity is the value or benefit given up by engaging in that activity, relative to engaging in an alternative activity. More effective means if you choose one activity (for example, an investment) you are giving up the opportunity to do a different option.

As it relates to the fourth law, I always told students that it doesn't matter whether we are talking about an ecosystem or society, somebody somewhere somehow is going to have to pay the cost. When an article like this promotes "free money", it is important for students to realize this "free money" is tax-payer money...their money. There is nothing "free" about it. It is important for students to understand this is their tax dollars being put to work and consequently may not be able to support other programs