SINGAPORE - A mural at Yishun Secondary School depicts scenes of old and modern Singapore. Trams contrast with today's MRT. A line of people queue for water rations, against people drinking Newater.
Art teacher Alan Wong Hiong Boon painted it in 2008 with the help of students. He says he did it to tell students that everything is now "made for them", unlike in Singapore's early years, and they should not "just enjoy the opportunities but use the opportunities to do more for themselves".
He ought to know. The adjunct teacher, who painted two other murals in the school, is still going strong at 81. He teaches students of all levels in Yishun Secondary. He is in school from 7.30am to 2.30pm every day and would say only that he is paid by the hour.
The active octogenarian hopes he can help young Singaporeans "appreciate art as a way of life".
He says: "Out of 40 students, one or two may become artists, the rest will know the value of good art. Maybe they can become collectors and so the professional artists can earn a better living."
His teaching career began in 1951, when Singapore was still under British colonial rule. He went to the Teachers' Training College after his O levels. He first taught all subjects at primary school level, then history, geography, English and art at what is now Serangoon Secondary School.
In the 1960s, he worked at the National Youth Leadership Institute, which trained youth leaders, and in the late 1960s, after the nation's independence, became a training officer in the civil defence force where he devised training programmes.
He rose in the ranks and in 1983, retired as the force's deputy commandant.
But he never truly retired. He worked as art director at an events company for a few years. By the late 1980s, he returned to schools as a relief teacher. The spontaneous and sporting Mr Wong also landed cameo acting roles in student films and TV shows such as Triple Nine, Growing Up and Incredible Tales.
Always challenging himself, he signed up for the Mr Senior Singapore 2010 competition organised by the People's Association's Active Ageing Council, which searches for active agers, and came in third.
On his varied interests and pursuits, he says: "My philosophy is do what you are supposed to do and then a bit more."
Mr Wong, who walks with a spring in his step and climbs stairs with ease, says he also uses art "as a means to promote national education".
Recently, the World War II survivor was invited to share his sketches of the Japanese Occupation with recruits of the Guards unit at the army's Bedok camp. He was 10 years old when Singapore fell.
Says Ms Ng Ngoing Keng, 54, principal of Yishun Secondary: "When he talks about the Japanese Occupation, it is real and authentic and students understand it better. With his artistic skill, he can also make his experiences visible."
She adds: "Mr Wong is not only a role model to students but also to teachers. He is full of passion in transferring his knowledge."
Mr Wong, who is married to a retired jewellery designer and has two sons in their 30s, says he will teach and challenge himself for as long as he can. "I'm like a coin still in circulation, still trying to hold value."