Depending on their schedules, Muslims probably will not need to perform all five prayers while on the job since the prayers are spread throughout the day. In addition, each of the five prayers has a window of time during which each prayer can be performed. This time frame extends from about one hour to as long as four hours depending on the specific prayer and the time of year, since the times shift depending on the season and length of the day.
Throughout most of the year, the prayer time for the noon prayer does not end while students are at school, so they can perform it when they return home. During the time of year when the prayer time ends while students are still in school, they can take a few minutes during recess or lunch to pray. Students can ask their teachers if they can pray in the classroom or library.
In the case of Muslim firefighters, if they are in the midst of fighting a fire and are unable to take a break to pray, they will perform the missed prayer as soon as they are able to, along with the next prayer.