https://raisingchildren.net.au/school-age/development/development-tracker/6-8-years
https://www.nichd.nih.gov/newsroom/resources/spotlight/092914-factors-child-development
https://www.beststart.org/OnTrack_English/2-factors.html
https://www.readingrockets.org/article/selecting-books-your-child-finding-just-right-books