“…who does not have formal training on language learning and teaching?”
I privately taught a female adult student one-on-one who was born and raised overseas with very little knowledge of English language. I had developed her learning curriculum from scratch—including language assessment for all four areas of English acquisition domain, (i.e., reading; writing; speaking; and listening).
For Reading assessment: I had her read a very short story I know she will have some control expressing the information back to me without great difficulty describing the material—orally. After the reading, I gave her my own teacher’s prepared [reading with comprehension] multiple choice answer sheet—based on the story she had finished reading. I collected this assessment and was returned to the student for Informative Assessment.
Writing: I asked my student to write a short response from the short story she just read and was returned to her for Informative Assessment.
Speaking: My student was asked to respond to a Q&A learning format, orally—derived directly from the same story she had just read, (i.e., tell me what the story says how Cinderella handled the difficult situation with her step-mother and sisters—who forbid her from attending the ball at the prince palace).
Listening: A tape-recorder was on—to record the student reading-rate or voice—as she slowly read the short story and was replayed for comprehension emphasis and foreign accent refinement. I had also utilized the online English language listening websites as supplemental.
The above assessments were used to measure her proficiency—as well as for mastery and ease. I taught ESL in public school in my county [part-time] while I was completing my master’s program in TESOL—for professional studies. Please note that in public school the students’ learning materials are all provided by the school themselves and must be closely followed due primarily to end-of-the-year higher grade level passing promotion students’ assessments—per statewide law in my state. I was not permitted to create my own ESL curriculum development or ideas.
There are also countless language assessments now available that can be ordered—designed for ESL educators for purchase. Please click this site for sampling: https://www.casas.org/about-casas