A lesson can be designated as a “router” which routes students through the many lessons making up a complete course. A router is associated with a course. Students registered in a course which uses a router will upon sign-in be sent first to the router, not to the lesson specified by the restart information. A typical router might ask the student, “Do you want to resume studying the lesson you last worked on?” If the student says yes, the router executes a “jumpout resume”, which means “jumpout” of this lesson into the lesson mentioned in the tag, with “resume” having the special meaning “resume at the restart point”. If the student does not want to resume, the router might offer the student an index of available lessons. Suppose the student chooses a lesson on the list whose name is “espnum”. Then the router does a “jumpout espnum” to take the student to that lesson. (The -jumpoutcommand can be conditional.) Upon completion of lesson “espnum”, (by “end lesson”) the student is brought back into the router. If the lesson executed a -score- command, the router can use the corresponding value of system variable “lscore” to help decide how to route the student. The router might ask the student what he or she wants to do next, or the router might immediately take the student to an appropriate lesson.

Generally speaking, -jumpout- commands should be placed only in routers, not in instructional lessons. Following this practice insures that lessons can be plugged into routers on a modular basis. An exception exists in the case where one instructional package is spread over two or three physical lessons, in which case -jumpout- is used to connect the lessons.

A router can use up to fifty “router variables” (vrl through vr50) which are not affected by the instructional lessons. These can be used to keep track of which lessons have been completed, how many times they have been reviewed, how much time was spent in each lesson, etc.

Authors write and test lessons, and students study these lessons. Instructors choose lessons from the library of available lessons to make up a course for their students. Instructors also register students, monitor their progress, leave messages for the class or for individual students, etc. There is an “instructor mode” which makes it easy for instructors to do these things without knowing the TUTOR language. The instructor mode is based on a router coupled with a mechanism for setting up a roster of students. The options available through this router are sufficiently flexible to make it unnecessary in most cases to write specialized routers.

Authors have a number of special “terms” to help them in curriculum development. If you press TERM and type “step”, you can step through your lesson one command at a time. (A continued -calc- counts as one command.) This is extremely helpful in tracking down logical errors in a lesson. After each step, you can check the present value of student variables. There is also a -step- command which will throw the lesson into the step mode. The step features are operative only for authors testing their own lessons.

“TERM-cursor” provides you with a cursor which you can move around the screen using the “arrow” keys. Press “f” for fine grid or “g” for gross (coarse) grid. Also press “f” or “g” to update the display of the current cursor location. This facility is useful for deciding what changes to make in the positioning of displays on the screen.

“TERM-consult” notifies PLATO consultants of your request for help. When a consultant becomes available, he or she will talk to you by typing at the bottom of your screen. The consultant's screen has the same display you have on your screen. It is as though the consultant were looking over your shoulder as you demonstrate the problem. You can talk to the consultant by typing sentences at -arrow-s or by hitting TERM and typing. (If you press NEXT, and you have typed eight or fewer characters, your sentence will be taken as a -term- to look for in the lesson. Otherwise your line is erased so that you can type some more.) The consultants not only know TUTOR well but they have also had a great deal of experience in helping authors.

“TERM-talk” asks you for the name of the person you want to talk to, then pages that person if the person is presently working at a PLATO terminal. The person called accepts the call by hitting TERM and typing “talk”. The two of you can then talk to each other at the bottom of the screen, but neither of you can see what is on the rest of the other person's screen. If you want the other person to see all of your screen, press shift-LAB, which puts you into a mode similar to TERM-consult.

“TERM-calc” provides a convenient one-line desk calculator at the bottom of the screen. Authors get normal, octal, and alphanumeric results. To avoid confusion, students who use TERM-calc are not shown the octal and alphanumeric displays.