WHAT IS SAT?
The SAT is a standardized test widely used for college admissions in the United States. It was first introduced in 1926, and its name and scoring have changed several times, being originally called the Scholastic Aptitude Test, then the Scholastic Assessment Test, then the SAT I: Reasoning Test, then the SAT Reasoning Test, and now simply the SAT.
The SAT is owned and published by the College Board, a private, nonprofit organization in the United States. It is developed and administered on behalf of the College Board by the Educational Testing Service. The test is intended to assess a student's readiness for college. The SAT was originally designed to be not aligned to high school curricula. Compared to its predecessor, however, the current version of the SAT is meant to reflect more closely the work that high school students do, according to David Coleman, president of the College Board.
The current SAT, introduced in 2016, takes 3 hours to finish plus 50 minutes for the SAT with essay, and as of 2014 costs US$52.50 (up to US$101.5 outside of the United States), excluding late fees. Possible scores on the SAT range from 400 to 1600, combining test results from two 800-point sections: Mathematics and Critical reading and Writing. Taking the SAT or its competitor, the ACT, is required for freshman entry to many, but not all, universities in the United States.
On March 5, 2014, the College Board announced that a redesigned version of the SAT would be administered for the first time in 2016. The exam reverted to the 1600-point scale, the essay was made optional, and students now have 3 hours to take the exam plus 50 additional minutes to complete the essay.
SAT consists of three major sections: Critical Reading, Mathematics, and Writing. Each section receives a score on the scale of 200–800. All scores are multiples of 10. Total scores are calculated by adding up scores of the three sections. Each major section is divided into three parts. There are 10 sub-sections, including an additional 25-minute experimental or "equating" section that may be in any of the three major sections. The experimental section is used to normalize questions for future administrations of the SAT and does not count toward the final score. The test contains 3 hours and 45 minutes of actual timed sections; most administrations (after accounting for orientation, distribution of materials, completion of biographical sections, and fifteen minutes of timed breaks) run for about four and a half hours. The questions range from easy, medium, and hard depending on the scoring from the experimental sections. Easier questions typically appear closer to the beginning of the section while harder questions are toward the end in certain sections. This is not true for every section (the Critical Reading section is in chronological order) but it is the rule of thumb mainly for math, grammar, and the 19 sentence-completions in the reading sections.
1. Critical Reading
The Critical Reading section of the SAT is made up of one section with 52 questions which should be completed in 65 minutes, with varying types of questions, including sentence completions and questions about short and long reading passages. Critical Reading sections normally begin with 5 to 8 sentence completion questions; the remainder of the questions are focused on the reading passages. Sentence completions generally test the student's vocabulary and understanding of sentence structure and organization by requiring the student to select one or two words that best complete a given sentence. The bulk of the Critical Reading section is made up of questions regarding reading passages, in which students read short excerpts on social sciences, humanities, physical sciences, or personal narratives and answer questions based on the passage. Certain sections contain passages asking the student to compare two related passages; generally, these consist of shorter reading passages. The number of questions about each passage is proportional to the length of the passage. Unlike in the Mathematics section, where questions go in the order of difficulty, questions in the Critical Reading section go in the order of the passage. Overall, question sets near the beginning of the section are easier, and question sets near the end of the section are harder.
An example of an SAT "grid-in" math question and the correctly gridded answer.
The mathematics portion of the SAT is divided into two sections: Math Test – Calculator and Math Test – No Calculator. In total, the SAT math test is 80 minutes long and includes 58 questions: 45 multiple choice questions and 13 grid-in questions.
The multiple choice questions have four possible answers; the grid-in questions are free response and require the test taker to provide an answer.
The Math Test – No Calculator section has 20 questions (15 multiple choice and 5 grid-in) and lasts 25 minutes.
The Math Test – Calculator section has 38 questions (30 multiple choice and 8 grid-in) and lasts 55 minutes.
Several scores are provided to the test taker for the math test. A subscore (on a scale of 1 to 15) is reported for each of three categories of math content: "Heart of Algebra" (linear equations, systems of linear equations, and linear functions), "Problem Solving and Data Analysis" (statistics, modeling, and problem-solving skills), and "Passport to Advanced Math" (non-linear expressions, radicals, exponentials and other topics that form the basis of more advanced math). A test score for the math test is reported on a scale of 10 to 40, and a section score (equal to the test score multiplied by 20) is reported on a scale of 200 to 800. 
All scientific and most graphing calculators, including Computer Algebra System (CAS) calculators, are permitted on the SAT Math – Calculator section only. All four-function calculators are allowed as well; however, these devices are not recommended. All mobile phone and smartphone calculators, calculators with typewriter-like (QWERTY) keyboards, laptops and other portable computers, and calculators capable of accessing the Internet are not permitted.
Research was conducted by the College Board to study the effect of calculator use on SAT I: Reasoning Test math scores. The study found that performance on the math section was associated with the extent of calculator use: those using calculators on about one third to one half of the items averaged higher scores than those using calculators more or less frequently. However, the effect was "more likely to have been the result of able students using calculators differently than less able students rather than calculator use per se." There is some evidence to suggest that the frequent use of a calculator in school outside of the testing situation has a positive effect on test performance compared to those who do not use calculators in school.
The writing portion of the SAT, based on but not directly comparable to the old SAT II subject test in writing (which in turn was developed from the old Test of Standard Written English (TSWE), includes multiple choice questions and a brief essay. The essay subscore contributes about 28% to the total writing score, with the multiple choice questions contributing 70%. This section was implemented in March 2005 following complaints from colleges about the lack of uniform examples of a student's writing ability and critical thinking.
The multiple choice questions include error-identification questions, sentence-improvement questions, and paragraph-improvement questions. Error-identification and sentence-improvement questions test the student's knowledge of grammar, presenting an awkward or grammatically incorrect sentence; in the error identification section, the student must locate the word producing the source of the error or indicate that the sentence has no error, while the sentence improvement section requires the student to select an acceptable fix to the awkward sentence. The paragraph improvement questions test the student's understanding of logical organization of ideas, presenting a poorly written student essay and asking a series of questions as to what changes might be made to best improve it.
The essay section, which is always administered as the first section of the test, is 25 minutes long. All essays must be in response to a given prompt. The prompts are broad and often philosophical and are designed to be accessible to students regardless of their educational and social backgrounds. For instance, test takers may be asked to expand on such ideas as their opinion on the value of work in human life or whether technological change also carries negative consequences to those who benefit from it. No particular essay structure is required, and the College Board accepts examples "taken from [the student's] reading, studies, experience, or observations." Two trained readers assign each essay a score between 1 and 6, where a score of 0 is reserved for essays that are blank, off-topic, non-English, not written with a Number 2 pencil, or considered illegible after several attempts at reading. The scores are summed to produce a final score from 2 to 12 (or 0). If the two readers' scores differ by more than one point, then a senior third reader decides. The average time each reader/grader spends on each essay is less than 3 minutes.
In March 2005, Les Perelman analyzed 15 scored sample essays contained in the College Board's ScoreWrite book along with 30 other training samples and found that in over 90% of cases, the essay's score could be predict