East Renfrewshire secondaries will also finish earlier on Wednesdays and Fridays, and there will be shorter lunch breaks. The additional space for the new timetable is made possible by the decision to use registration time to form three additional periods, with teachers taking registration electronically at the start of each class.
The changes are also intended to comply with the Scottish Executive's demand that all S12 English and maths classes have a maximum of 20 pupils by August 2007.
The S1 curriculum will continue to offer "rotations" of subjects in, for instance, the social subjects, technology, and creative and aesthetic modes. But, when pupils reach S2, they will be able to specialise earlier.
This means that East Renfrewshire secondaries will no longer offer integrated science in S2, but will give pupils the chance to study two discrete sciences, or a single science subject and a second modern language should they wish to.
In S3, pupils interested in following a more vocational route will be offered that as one of the eight modes. But, unlike some authorities, East Renfrewshire will not require them to miss classes in other key subjects such as English or maths.
In S56, the period allocation for all optional subjects will be increased from five to six periods, bringing them into line with English and maths.
The new timetable will also exceed the executive's recommendation that all pupils receive at least two hours of physical education per week, by adding another half-hour. The authority is promising to recruit more PE teachers.