In A sound of thunder a character says step on the mouse and you crush the pyramids what does it mean ?

Agroup of students are collaborating on an online research project. which is an example of appropriate online behavior? laura asks everyone to introduce themselves at the group’s initial meeting. nico sends a long e-mail introducing himself before the group’s initial meeting. benjamin sends a text to the group asking for usernames and passwords. julia posts notes with emoticons on a message board for the group to read.