1400's to modern day texts.
Changes to language over time.
Could be comparing two extracts OR just one extract.
Damp Tea Spoon Theory
Crumbling Castle Theory
Writing -> How children learn to write. National Literacy Scheme
Speaking -> Skinner. Halladay. Chompsky. CDS scheme & aims.
Reading -> NLS. School & home environment. Oxford Reading Tree. Not every child has the same environment & circumstances.