SINGAPORE - Ask observers what Mr Tan Chuan-Jin has achieved as Minister for Social and Family Development in the past two years, and the replies come fast and thick.

He started KidStart to help children from disadvantaged families level up.

He helped push for unwed mothers to get 16 weeks of paid maternity leave, like their married counterparts, instead of eight weeks. This took effect from Jan 1 this year.

He also worked to raise the profile of pre-school teachers.

Mr Seah Kian Peng, who chairs the Government Parliamentary Committee (GPC) for Social and Family Development, put it thus: "He is very passionate about social causes.

"It'll be a waste if that passion and conviction cannot be put to good use. Chuan-Jin has always had a heart for the less privileged, which includes the poor and elderly, but also people from broken families and single mothers."

The announcement on Tuesday (Sept 5) that Mr Tan would be resigning took observers in the social service sector by surprise, but they said they were glad that he would still be involved in the sector in other ways.

Mr Tan, 48, will be nominated as Singapore's 10th Speaker of Parliament by Prime Minister Lee Hsien Loong when the House sits on Monday (Sept 11).

But he will continue to oversee SG Cares, a national movement which encourages Singaporeans to volunteer, and will be appointed adviser to the National Council of Social Service (NCSS), where he is currently its patron. He will also continue to lead Marine Parade GRC.

Mr Seah said it was rare for a Cabinet Minister to be nominated as Speaker of Parliament. Mr Tan would be the second such minister to be nominated; Mr Abdullah Tarmugi was formerly Minister of Community Development and Sports and Minister-in-charge of Muslim Affairs before becoming Speaker from 2002 to 2011.

On the pre-school front, Chiltern House principal Iris Lim said she appreciated Mr Tan's efforts to raise the profile of pre-school teachers. For instance, from this year, childcare centres could close for an extra half-day. Mr Tan, when announcing this initiative last year, had called for childcare centres to give their educators a day off on Teachers' Day.

Mr Tan had also joined some pre-schoolers, from The Little Skool-House at Thomson and Chiltern House Thomson, to perform the song You Are My Sunshine in a video to pay tribute to early childhood educators. The minute-long video was posted on his Facebook page on Teachers' Day.

Ms Lim said: "I think that allowed teachers to know that he appreciates all of them, and it narrowed the distance between the teachers and the Government. He's quite a down-to-earth person."

Other people in the social service sector also said he was down-to-earth and engaged the community.

Mr Keh Eng Song, former chief executive of the Movement for the Intellectually Disabled of Singapore, said his Facebook posts can attest to how well he engaged the public. "Detractors aside, it does come across that he continues to engage regardless," said Mr Keh.

Mr Tan has written Facebook posts on a range of topics, ranging from photos of the cinnamon buns his daughter baked, to thoughts on why some working adults still need financial aid. He can also laugh at himself - in a post in April, he called himself a "suaku" ("country bumpkin" in Hokkien) for having not tasted Chinese preserved olive vegetables before.

Disabled People's Association president Nicholas Aw said: "Mr Tan invited me to lunch to talk about disability issues here, and he shared with me his personal experience of trying to navigate pavements using a wheelchair. His frank sharing about how difficult it is in some areas showed me that he's willing to admit when there is more work to be done. He's also willing to try new things and learn more by doing, even if it sometimes opens him to criticism, which is very refreshing."

Mr Aw said Mr Tan's varied portfolio in various ministries would give him a wide range of experience to tap on when facilitating debates. "His no-nonsense attitude will also come in handy when the debate goes off topic," said Mr Aw.

Mr Tan's previous appointments include Minister for Manpower (May 2014 to April 2015) and Senior Minister of State for National Development (August 2012 to September 2013).

Mr Desmond Lee, 41, will take over from Mr Tan and remain Second Minister for National Development, but relinquish his posts as Minister in the Prime Minister's Office and Second Minister for Home Affairs.

Ms Jolene Tan, head of advocacy and research at the Association of Women for Action and Research, said Mr Tan had also engaged civil society organisations.

She said: "We're pleased to have opportunities to collaborate with him on shared interests such as ending domestic violence and promoting active fatherhood.

"Crucially, his tenure at MSF saw important movement towards achieving inclusion for single-parent families... We hope Mr Desmond Lee will build on this to tackle the major outstanding challenge of housing for single-parent families, which he is well placed to do given his experience in the Ministry of National Development."