What are the required idioms for the SAT? And what is the best way to learn/study them and then use them on the actual test?
Don’t worry about idioms. Studying other topics will have more impact.
There are hundreds if not thousands of idioms that may be tested on the SAT. Its not worth studying them. There will be very few questions where the knowledge will be applicable. I think most students who study rigorously for the test targeting a perfect score, do not study idioms.
Vocabulary is much easier to study than idioms, and more likely to be considered positively.
Many idioms are considered jargon a.k.a. informal, so I would steer clear of idioms in the essay. As for actually understanding questions, reading and reading and reading SAT study materials is important, then making sure to note any words or phrases you don’t know, then look them up.
Idioms are cultural, short cuts we use when speaking. I have never seen them listed. We just know what they mean and use them without thought. Years ago, I had a student from China enrolled in a stats class who asked me to define words (easy) and explain idioms. Some idioms like rule of thumb are difficult to explain. I can’t think there are many idioms on these tests because they are culturally bound and the tests are used internationally.
There are many idiomatic phrases that will appear on the test, and they are not strictly like the one mentioned above. As…as… comes to mind. We also say not only…but also, between…and, either…or, neither…nor. There are any others.