Question

When conducting an experiment on time management, jamie assigns everyone who arrives before noon to the experimental group and everyone who arrives after noon to the control group. in the context of experimental research methods, what is wrong with jamie's experiment?

Answer 1

According the context of experimental research methods, it is wrong that Jamie has not used random assignment.
Because Jamie assigns everyone who arrives before noon to the experimental group and everyone who arrives after noon to the control group there is no randomness in the data he gets from the experiment. 
Using random assignment would be if Jamie assigns the participants to different groups no matter when they arrive, (using randomization). 

Answer 2

Jamie should have used random assignment to split the people up. Random assignment would eliminate the possibility of Jamie splitting up the people based on certain characteristics or bias. It would give everyone an equal opportunity to join either group and prevent major differences from forming between both groups.