My mom's uncle and his wife were Northern Missionaries to the mountains of northeast Tennessee. The ministry with which they served (& which he later directed for decades) also ministered in southwest Virginia.
They had association with similar ministries throughout southwestern Virginia and southeastern Kentucky. I grew up hearing (great-) Uncle Martin telling of his friends working in the various camps & ministries that dotted the southern Appalachians. There was sometimes a flow of workers from one camp/ministry to another.
In my experience, most of the missionaries were from the north, they lived by faith trusting God to provide for their needs (no salary was promised from any organization and neither did they mention financial needs, instead trusting the Lord to supply), they taught Bible in the schools, they started Sunday Schools in hamlets where there was no Sunday worship, they received missionary barrels from the north with donated clothes, quilts, etc. that were of immense help to the southern folk, and they started summer Bible camps. These Northern missionaries also traveled back home to the North regularly (annually?) on "deputation."
If school children memorized so many Bible verses in a year, they earned a free week of Bible camp. As late as 6th grade, I remember the Bible teachers coming to our school once a month to teach the Bible, using flannelgraph stories. In elementary school I remember memorizing the first verse (or verses) and earning a little booklet of verses, and then memorizing those and earning a Gospel of John. One could later earn a New Testament.
Imagine my surprise to hear, when BK joined youth group this summer, that there is a Scripture memory challenge. Any student who memorizes three consecutive chapters of the Bible gets a $75 discount off the registration cost for fall retreat!