I am looking for a fun and engaging teakwando class as well as dance/movement class for my 3.5yo boy. Any recommendations?

Such a good idea! My son went for aikido when he was your son’s age, holiday classes provided by a partnered martial arts school. So if your boy is in a playgroup, look out for holiday programmes for martial arts and dance. In the meantime, I think these would be good references: https://sg.theasianparent.com/best-martial-arts-classes-for-kids-in-singapore/ Sports Hub should be good, no? http://www.sportshub.com.sg/Venues/Pages/Kids-Dance-Class.aspx