FIRST BATCH
In 1974, the Council for Indian School Certificate Examination, granted the school affiliation, thereby enabling it to present its first batch of students for the ICSE examination the following year.

In 1986, the second part of ICSE, i.e.,Indian School Certificate, was added. This pattern of syllabus continues.

A WELCOME CHANGE
Two years after the school was initiated, the admirers of Mr. K.I. Thomas founded the KIT Thomas Educational Society, a registered christian minority trust, as a tribute to his contribution in bettering the society. The Trust now owns and controls the management of the school. The very next year 1975, the school was shifted to a five acre premises in Ramalayam Annexe, purchased for Rs.14 lakhs raised through loans. This proved to be a farsighted venture, for the property is today beyond ordinary resources.

GROWING YEARS
1984 heralded a new chapter in the history of Sishya. A new block costing 14 lakhs was constructed, which houses the Senior School and the Laboratories. This amount was raised primarily through donations received from parents and well wishers of the school.

In 1989, the Junior School- cum- Auditorium block, costing Rs. 21 lakhs was constructed. This was possible through the efforts of the Sishya PTA which was established in 1985. Since then, the PTA has been actively helping the school in all activities, 'EXPOSISH' 1988, a novel fund raising effort initiated by the PTA, was a massive project in which the parents, teachers and also the students played a major role, and was a resounding success. The Junior-School cum Auditorium was designed to be multi-purpose in function, and since construction, has been put to extensive use.

In 1991, the Preschool Complex for Classes LKG, UKG and I was inaugurated. These cottages built in a novel architectural style are set in sylvan surrounding with its own kiddies play ground. The major contribution towards its construction came from ITC which has had a close relation with the school for many years.It has been named the Grace Cherian Memorial ITC Pre-school block.

In 1994 the playground was completely re-laid and re-surfaced and converted to facilitate athletics and games even in the rainy season This was originally the lake of the Ramalayam annexe which was reclaimed.

CONSOLIDATION
In 1997, on the school’s Silver Jubilee, the new Library Block was inaugurated and named The Thangam Thomas Library Block after one of the school’s co – founders. This building houses the Library including an extensive multi media computer section, the Art Dept. and the classrooms for the Plus 1 and Plus 2 Sections. The moving of the Plus 2 classes created more space in the Senior Block and a new Biology Lab. was opened.

In the following years, the Management found that owing to lack of space, we were turning away many children who would have done the school proud. After much debate, it was decided to add a third section to each class. Each section would have only 30 children so that the school would have the benefit of more admissions while keeping the strength of each section to an optimum number of students.

In order not to compromise the open area and the playground, the old school auditorium was replaced with a new building housing the new auditorium, Computer Labs, Maths Lab, and the Junior School classes. This building was completed and inaugurated in 2006.

In 2010 , in association with the CL Metha Trust, the Dr. C.L. Metha Sishya OMR school was opened in Thoraipakkam on the OMR. In 2011 the Ecole Franco Indienne was opened in the main school campus.