Question: what to do with a 4 year old?
Answer: Build an obstacle course. An obstacle course is a great way to stimulate physical and mental coordination. ... 
Hide-and-seek stuffed animals. A fun twist on an old favorite is a hide-and-seek game using stuffed animals. ... 
Make your own Play-Doh. ... 
Build a castle. ... 
Arts and crafts. ... 
Fantasy play. ... 
Don't forget classic games.