According to the excerpt, what was one of Levin’s worries when he began using Minecraft in the classroom?
He worried that parents would think he was wasting time. He worried that his principal would not support gaming.
He worried that students would become bored with the game.
He worried that students would not purchase the game.

martians or other types of aliens represent a unique fear as opposed to zombies. vampires and other types of monsters.   in most sci-fi stories, aliens come from other worlds and have different or more advanced technology.   abductions and experimentation on human bodies that involve these technologies, or the use of these technologies against human beings and the use of unknown "powers", are a type of fear that's different from that of other types of monsters.  

the mending wall was written by robert frost

it makes the game seem more impressive.