There are many adults who do not know how to read. There are many reasons why they never learned. Some never went to school. Some learned to read a little, but not well.
Adults are the fastest learners.
They already have pieces of the puzzle.
They need someone to show them how to fit all the pieces together.
Undiagnosed visual development issues are often the main reason why some adults are illiterate.
Carola screens adult students for vision development.