In my opinion it is more efficient to write a to-do list on smartphone rather than on paper in a notebook. There are some reasons why I think so.
There are many personal organizers, notebooks and diaries which are made of paper in the markets today. They are created  in different shapes and sizes, paper types and colors. They are nice outside and well-organized inside. Despite <strike>of</strike> so many positive aspects of having a paper notebook I give my preference to built-in notebook in my phone because of its cost. The average price for good notebook is thirty dollars and for a notebook on a phone is free of charge.
Additionally, I noticed when I use a paper notebook I spend more time writing  down things I have to do in a day. I constantly have to open it to take a look at <strike>a</strike> tasks, cross it out when I am done with it, and remind myself to do it over and over again during the course of the <strike>a </strike>day. Apparently, it takes more time than writing everything down on a smartphone and setting a notification for each task without getting distracted on these things. What is your choice to keep things organized?

i think if she was speaking to a child she was probably trying to teach a lesson to the child to see if he or she actually knew if it were two or three elephants