Delving into the world of homework planners.
An ordinary school diary only shows when stuff has to be done. And has not much space for planning tasks.
Found a few diaries that have the space for days cut in two. One to write down homework, and check whether you got it finished or planned. And below or next to that a place to write down the planning on what to do about it, on what day. Cutting tasks into smaller bits.
Looks pretty effective.
Will try it with kid.