So, ecosystems.

Basic concept but Nina didn't knew how to explain. Heh. She raised her hand before answering and said "Umm... ecosystems are...well they are composed of living and non living organisms that interact with each other and..." AND? "And with their surroundings...err...environment" Did it made sense? Hopefully.

And did the professor just said they'll be moving around? Nina was kinda eager to know what they would be doing so she took out her notebook and quill.