The current crop of HSE exams (GED, TASC, and HiSET) differ somewhat in their form, but cover virtually the same academic material:
Language Arts: Reading
Language Arts: Writing
Mathematics is the dominant theme throughout the program. Nearly thirty of the thirty-five study units include math assignments. There are two reasons for this: (1) it is the weakest subject for most people starting the GED & College Prep program, and (2) it is the most skill-intensive subject on the HSE exams. In brief and plain language, if you don't master the math, you aren't likely to pass the exam.
For your information, the HSE exams will be evolving through year 2020 to require math perspectives and skills required by the Common Core Standards initiative now being implemented in the USA education system. Of course Common Core Standards are reflected in the nature of the math assignments for this GED & College Prep program.
Language Arts: Reading. People entering high education and the contemporary workplace as expected to be able to comprehend what they read; and tests of reading skills aren't limited to the Language Arts portion of the HSE exams--most of the prompts for the Science and Social Science portions of the exams are actually tests of reading comprehension (and mathematical) skills. Exercises in reading comprehension and scattered throughout the study units.
Members of the GED & College Prep program are expected to read at least one American novel and study a series of documentary films. How does that help with HSE exam prep? It sharpens the wits. It's not what you learn directly from these assignments, it's how the exercise (if executed according to the spirit of the project) changes the way you think, absorb information, analyze it, and communicate it to others.
Language Arts: Writing. This portion of the HSE exam (and the preparation for taking it) includes grammar, sentence structure, and writing style. A lot of the prompts for Language Arts: Reading, Science, and Social Science require short essay-type responses. These responses are graded, not only for their relevance to the Science or Social Science prompts, but also the quality of the writing.
Of course you will be doing some assignments that deal directly with spelling and grammar, but most of those skills are acquired indirectly -- by doing a lot of reading, writing, and communicating effectively with classmates.
Science. You really don't have to carry very much science knowledge into the HSE testing session. Most science questions on the HSE exams are actually tests of reading comprehension, analysis of ideas, and ability to communicate conclusions.
As part of a GED & College Prep class, you will be watching online videos and reading material that give you some perspectives on science topics and the way science works in general. But you don't need to memorize all those names and functions of the little organelles that occupy the inner world of living cells.
Social Science. As with the Science portion of the HSE exams, you don't have bring a head full of history, civics, and psychology into the testing room. Virtually all facts are provided on the test, and it is your job to sort out the facts and the relationships between them. That perspective is carried through the study units for the GED & College Prep program.
Of course there will be brief assignments that show each participant what to expect when sitting down for the HSE exams. Will the exam be on paper or computer? What about using a calculator? Where do I go for the exam?