Morgan who is free on $10,000 bail arrived at court with several family members, who declined comment.
Defense attorney Peter Lowe told reporters after the hearing, "We're not going to have any comment at this time."
Morgan is to appear in front of Judge Michael Lyon on Feb. 23 at 2 p.m.
Morgan and a 16-year-old student, both seniors at the high school, had planned to set off a bomb during a school assembly, then steal an airplane and fly to another country, according to police.
Searches by police turned up no explosives. However, the statute with which the students are charged includes the language "... or conspires to use a weapon of mass destruction ..."
Police were notified of the plot when a student came forward after receiving a text message from the 16-year-old suspect, asking her whether she would stay away from the school on a specific day if he asked her to do so.
The 16-year-old boy told police he had experience making a pipe bomb using "gun powder and rocket fuel" and that Morgan had three guns in his home, according to court documents.
The 16-year-old was charged Tuesday with the same count as Morgan, but in 2nd District Juvenile Court.
On Tuesday prosecutors also filed a motion to certify the 16-year-old boy as an adult.
"These offenses were especially serious given the fact that the offense was directed against the entire student body and staff of Roy High School as well as a threat of extensive property damage," prosecutors wrote in their motion. "The defendant's emotional attitude, pattern of living, environment and home life demonstrate that he has sufficient maturity to appreciate the seriousness of these charges and to be tried as an adult."
If the 16-year-old is certified as an adult, his case also will be assigned to Judge Lyon, West said Wednesday. The Salt Lake Tribune generally does not name juveniles charged with crimes.