manual labor like field work, house work, baking, tailoring, keeping a shop, etc are things you can do while watching kids. you take the kids to work, and let them play alongside you. when they are old enough they can help, or pretend to help.

if your work requires focus like writing or programming, then kids are a disruption and you can't do it.

also once factory work was developed, schools for everyone were built too, those developments happened at around the same time.