I’m not much of a museum person, but if you’ve got a kid, give this one a go. I would especially recommend the Future World - an immersive art and science experience specifically designed for little ones. You’re welcome ;)
Pro tip: Keep an eye out for the exhibitions as held in conjunction with Team Labs. Great spot to rent cycles and explore the nearby Gardens by the Bay. Or if you’re feeling lazy, swing by the alfresco restaurants and indulge in a cold lager with a stunning view of the financial district.