What do you mean by "On paper"? If your students are continually reserving rooms and checking availability throughout the day, wouldn't you do all this on a computer screen?
Assuming that is the case.
Two tables: Rooms, 1 record represents 1 room and Reservations, 1 record represents the shortest block of time a student can reserver for a given room (1 Hour or 1/2 hour is my guess from your description).
In Rooms, you need at least one field: RoomID--either a room number or an auto-entered serial number. If you use a serial number, add a second field for the room number.
In Rooms, you need at least three fields: RoomID, TimeSlot, StudentName
One relationship: Rooms :: RoomID = Reservations :: RoomID
Set up a rooms layout where you can see all pertinent fields about the room. Add a portal to Reservations. Set your portal up to be sorted by time slot in ascending order.
Now you can reserve a room by finding that room record on your layout and entering the student's name in an open time slot.
That work for you?
Your say is very basic and not accurate regarding validation. In this case the tables will be as follows:
Can there be a validation on Room_ID, Reservation_Date, and Reservation_Time assuming the reservation is for 1 hour?
Sorry for bothering you guys but I need to know if this validation is possible in version 9!
Try adding a text field to the Reservations table that auto-enters the concatenation of room ID, date and time (replacing existing value). Validate this field as unique, validate always.
This is assuming reservations always start on the hour and last an hour - otherwise you'll need to validate against a self-join relationship of overlapping reservations.