Toys with interlocking pieces (ex. Mr. Potato Head).
a tray on a high chair; wheels on the bottom of cribs; wheel of a carriage;
(Squeezing materials.) understanding the concept of squeezing out human hair, toothbrushes, baby bottle, etc.;
Using nice smelling liquid soap, placing lavender flower bars and other essence of deodorizers into drawers or closets, and putting unscented powder into shoes...