What activities do you do to engage your 3-month-old baby?

You can sing nursery rhymes about body, and touch your baby's body parts mentioned in the songs. Also you can make flash cards using black and white colors, because infants prefer sharp contrast-color images at this age. You can download and print it yourself, or just buy online from amazon/lazada etc. This link offers free download for the flash cards: http://www.brillbaby.com/free-download/infant-stimulation-cards.php