What do you do to keep your kid busy while working at home?

It depends on how old is your kids. For my 4 years, I will print some math questions, colouring worksheet or setup some experiment for her to do. Normally the experiment like mixed colours or shaving cream painting which can keep her busy for quite some time. For my 15 months, I will let her sit in front of the computer on my lap with a keyboard that does not connect to my system to work on or let her crawl around with toys around her to play.