After his retirement from
Lawrence School, Lovedale, K.I. Thomas began a nursery-cum-preparatory school, in January 1972, with a first batch of 28 pupils. In 1974, the
Council for the Indian School Certificate Examinations, 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 the ICSE exams were added, allowing the school to teach 11th and 12th grades. 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 to bettering society. The Trust now owns and controls the management of the school. The very next year, 1975, the school was shifted to five-acre premises in Ramalayam Annexe, near the Ramalayam Palace of the
Travancore Family. 1984 saw the addition of a new block to house the senior school and laboratories. In 1985, the Sishya
Parent-Teacher Association was established, and by 1989 had raised enough money for the creation of another block, and an auditorium. In 1991,
preschool, and
kindergarten classes were started, through donations from
ITC. In 1994, land from the lake on the premises was reclaimed, to create a playground. In 1997, a library block was added. In 2006, the auditorium and surrounding blocks were renovated, to keep up with the increase in capacity of the school. 2010 saw the creation of a new, better and more sophisticated branch, in association with the C.L. Metha Trust, the Dr. C.L. Metha Sishya OMR School (now renamed as Sishya OMR School) on the
Old Mahabalipuram Road. In 2011 the
École Franco-Indienne Sishya was opened in the main school campus. ==Events and activities==