We should have left them alone.

Part 1: Unit Intro

Professor Galgrax sat in his chair, manipulating the spherical interface to the computer. He was making some last-minute preparations for the lesson. Under ordinary circumstances, this would be unheard of for a teacher at the Verthun Military Academy. Like the students that attend, they were expected to be the pinnacle of skill and knowledge, and for one to not have the day's lesson prepared in advance was a scandal.  However, these were no ordinary circumstances. He glanced over at the now-full classroom, and at the watch on one of his tentacles.

"Good morning, class. My apologies for the delayed start. Today, we will be starting a new unit." As expected, a dozen appendages extended into the air. Galgrax sighed inwardly. The downside of creating a school filled with the best students their respective worlds can muster is that a good third of them seemed dependent on the system and schedules to function, usually the ones from the non-warrior races. He arbitrarily picked one of the hands, knowing they all had the same question. "Yes, you in the back, the bhryali with the orange fur."

"Professor, the schedule we were given for this Xenology class showed there wasn't a new unit for another two weeks."

"Yes, the administration felt that we needed to have a short unit taught immediately on the newest species on the galactic scene, as of six days ago. Thus, they shoehorned it in right in the middle of another unit."

"Um, 'Shoehorned", Professor?" the Bhryali girl asked quizzically.

"An expression from the species we will be studying." Galgrax replied quickly. A single claw rose, this one belonging to the Attarian named Krex. Galgrax gestured for him to answer with one of his tentacles, while finishing the link between the plasma projector and his computer.

"What new species do you speak of, and what have they done to merit the level of priority? When the Attarians arrived," Krex continued in an incredibly smug tone, "it took years of being integrated before we were placed into the curriculum, and we're the most dangerous race in existence." 

"Debatable." said the Professor, causing a few giggles through the classroom. He stood from his chair at last, his multitude of limbs drawing him up to full height. "But good question. Lets go through it. What are the four traits that a planet must not have to be capable of supporting advanced life forms? Yes, you in the purple."

"It cannot have more than 126 vytuns of radiation from its star per cycle per square lumtar." answered the student.

"And why is that?"

"To prevent certain atmospheric conditions. If it has too much incoming radiation, it causes convection, leading to hot and cold spots, and possible storms."

"Very good. Yes, the Draera in front."

"No magnetic field is the big one. The interference stops the evolution of brains, as it messes with the magnetic pathways and removes their evolutionary viability."

"Correct. It can even stop colonization by existing races if it's strong enough." He pointed at another student with a tentacle up. 

"Fifty percent or more of the surface must be solid. Otherwise, it's statistically impossible for life to form on it."

Professor Galgrax nodded, before gesturing at a student for the final answer. "And the last one?"

"It must not be very tectonically active, lest a copy of the Scourge bacteria wipes them out."

"All of you are correct. These factors make a world impossible for advanced life to form on them. The species we will be studying is known by the name 'Human', and are unlike anything we have ever seen. Concerning these traits, the Human home world..." He paused for dramatic effect, "Has ALL of them."