Those who lived in poverty often had large familes, simply because the expectation (and the reality) was that at least some would die. In 1900, the biggest killer of children in the UK was diarrhoea & sickness.
April 1917. "Daily inspection of teeth and fingernails. Older pupils make the inspection under the direction of teacher who records results. This has been done every day this year. School #49, Comanche County, Oklahoma (near Lawton)."
"First and second grade pupils in 1950 carry school supplies from their old one-room school house in Riley Township [Ohio] across the field to a new school." ~ Children's games of the time: http://www.oneroomschoolhouses.ca/the-games-they-played.html More games: http://thelibrary.org/lochist/periodicals/bittersweet/fa73l.htm