Follow the below path to create the Master subjects.

SIS --> Subjects --> Subject Creation --> Master Subjects / Subject Groups

Note:
Master Subjects feature helps the school to group the subjects that are used across different academic years to one Master Subject.
This will help the system to map the performance of a student across all academic years in the subjects that are mapped to a master Subject.

Example:
Create a master subject as Mathematics.
Let's say, you had the following subjects in different academic years.
2016-17 Grade1 - mathematics
2017-18 Grade2 - General Maths
2018-19 Grade3 - Mathematics
2019-20 Grade4 - Maths
Map all these subjects to the master subject Mathematics.
Now, the system will show you the comparative analysis on students performance in Mathematics subject for 4 years [ From Grade 1 to Grade 4].