Made me think of a wine offering. The wiki entry on libation (scroll down to ancient Greece) is a decent summary: https://en.wikipedia.org/wiki/Libation Libations aside, spiritualities that see the interconnectedness of everything are common today and throughout human history, and IMHO those spiritualities have a lot to teach people who have been socialized to see humans as separate from and superior to creation and fellow creatures. In indigenous spirituality of north and central western hemisphere, for instance, it's not uncommon to talk to flowers. Using pesticides and destroying the earth and our health = bizarre; not bizarre = thanking the interconnecting spiritual life/beauty that is nature.
In my somewhat outdated dictionary, it adds the word "enjoy oneself" to the definitions of the verb ευχαριστώ, or rather, to its reflexive form. Ευχαρίσηση means "pleasurable", so I think a reasonable english translation might be "Our parents take pleasure in nature." Or "Our parents delight in nature." That might not fit in well with the direction of the course, though.