Mr Siow Chin Lam, 69, has spent nearly five decades in Crescent Girls' School in Tanglin, and has no regrets.

Mr Siow, who joined the school in 1966, said: "I have fond memories of Crescent, and I know every nook and cranny of the school."

The geography and English teacher retired in 2008, but signed on almost immediately after that as a contract adjunct teacher to continue teaching.

"My principal asked me if I needed a break but I wanted to continue working, as long as I have the energy," said Mr Siow.

"It's nice to be acknowledged when my ex-students come up to me in hospitals or supermarkets to greet me," he added. "Some of them even say hi on Facebook."

Mr Siow, one of Crescent Girls' longest-serving teachers, appears in an old, black-and-white photograph which is displayed along a corridor in the school that serves as its heritage gallery.

The $60,000 gallery, which was completed in September last year, features the school's milestones since it opened in 1955 as Alexandra Estate Secondary School, a co-educational school.

Eventually, the male students were transferred out, and the school adopted its current name in 1956, from a nearby estate, Prince Charles Crescent.

In 1996, the school was given autonomous status, which gave it greater freedom and funding to plan programmes for its students.

It is known for its strength in adopting information technology in classes, as one of the pioneering schools in 2007 under the Ministry of Education's Future Schools project. These schools are designated as test beds for teaching approaches that use educational technology.

Also on display in the gallery are items contributed by alumni, such as old school badges designed by staff and students in the early years, an old handwritten register of students' names and their family details that was used in the 1950s and 1960s, and awards from former school athletes.

The gallery also features photos of the school's former principals and prominent alumni, such as Ms Ho Ching, wife of Prime Minister Lee Hsien Loong. She graduated from the school in 1969.

Secondary 3 student S. Darshana said the information panels on the principals struck her the most.

"Starting from Ms Evelyn Norris, Crescent's first principal, we see how the school has changed, and what the previous principals have done for it," she said.

Another Secondary 3 student, Estella Tan, said learning more about her school has given her a "stronger sense of attachment and school identity".

"My biggest memories of Crescent will be the friends I've made here and the school spirit," she said.

Amelia Teng