'put the big rocks in first' - plan time slots for big important tasks, otherwise urgent small demands will leave no space
Use this time management story to show/understand how planning of tasks is the key to time management.
Start with a bucket, some big rocks enough to fill it, some small stones, some sand, and water.
The bucket is your available time. The rocks, stones, sand and water are your tasks - a few big ones, some more medium-sized ones, and lots of small jobs and continuous demands and interruptions.
Put the big rocks in the bucket - is it full?
Put the small stones in around the big rocks - is it full?
Put the sand in and give it a shake - is it full?
Put the water in. Now it's full.
The point is: unless you put the big rocks in first, you won't get them in at all.
In other words: Plan time-slots for your big issues before anything else, or the inevitable sand and water issues will fill up your days and you won't fit the big issues in.
Note that a big 'task' isn't necessarily a work task - it could be your child's sports-day, or a holiday.