"Necessary homework" refers to the work or tasks that someone has to do for a specific reason or purpose. It is important or required work that needs to be completed. Full definition
«Anyone too young to remember the heyday of color field painting should regard Hackett Mill's show of early work by Jules Olitski (1922 - 2007) as necessary homework. (twocoatsofpaint.com)
Two drawers act as storage for necessary homework essentials, without being too big or deep to allow them to become bottomless pits of random stuff. (wcollectiveinteriors.com)
Olitski's «Circles»: Anyone too young to remember the heyday of color field painting should regard Hackett Mill's show of early work by Jules Olitski (1922 - 2007) as necessary homework. (chron.com)