You’ll need to bring valid identification (photo ID, SSN card) to be admitted into the ASVAB testing room. Arrive on time— you’ll be turned away and required to reschedule if you are late. Your recruiter may give you a ride to and from the session, but he/she is not permitted in the testing room. You will not need to bring a calculator for the test.
In the 1950s, the military adopted a single exam known as the Armed Forces Qualification Test (AFQT). Used as a screening tool, the AFQT measured a recruit’s ability to absorb military training and their future potential. It was supplemented by service-specific battery tests for the purposes of MOS classification. In 1972, the Department of Defense determined that all services should use one exam for screening and assigning individuals to an MOS. The AFQT was phased out over a two-year period in favor of the current Armed Services Vocational Aptitude Battery (ASVAB) test.
In complete honesty, one can say that the test identifies with an entire life's worth of knowledge. It essentially pulls from 3 different aspects. First, it draws from concrete facts that were acquired from all areas of a person's educational career. Secondly, it draws from a person’s ability to comprehend and use context clues to make assumptions. Lastly, it draws from a person’s physical/verbal skills to see if they can properly administer those more physical aspects. Overall this is why people have identified it as the “SAT on steroids.”
The Auto and Shop Information section of the ASVAB test measures your knowledge of automobile technology and basic repairs. The shop questions are about basic wood and metals. For example, you will encounter questions such as “Shock absorbers on a car connect the axle to the: wheel, chassis, drive shaft, or exhaust pipe?” You may be asked what sanding blocks are used for, followed by the following choices: preventing high spots and ridges on sanded surfaces, preventing dirt from collecting on the sandpaper, stretching the length of sandpaper, or prolonging the use of the sandpaper. The CAT-ASVAB test has two parts: the first part covering automotive material asks 11 questions in 7 minutes; the 11 shop information questions are allotted 6 minutes. The paper-and-pencil version asks 25 questions in 11 minutes.
All test takers are given a summary results sheet that shows their percentile score in every test area. A percentile score of 50 means that a score was achieved that was better than 50 percent of all test takers. Percentile scores are given specifically for test takers of their gender and their grade level. Information obtained from the test is only shared with agencies within the Department of Defense. Test takers are informed that their specific scores will be used for up to two years for recruiting purposes. After two years, test scores will be used for research purposes only.
To be admitted to the ASVAB testing room you will need to show a valid id. It is also important to be on time (or early!) since you will be turned away if you show up after the scheduled start time. The ASVAB can be given via computer or pencil and paper.  If you are testing at a MEPS site you will take it on a computer.  The pencil and paper version is given at most MET sites.  The computer version of the test is given as a "computer adaptive test" (CAT) which means that the test will adapt based on the level of the individual test taker (e.g., if you answer many questions correctly, you may be shown fewer questions).
The ASVAB is routinely reviewed to eliminate any potential biases from questions and scoring. The exam underwent a major revision in 2002. Two years later, a renormalization of the percentile scoring system was performed to ensure that a 50 percent score represented performing better than 50 percent of all test takers. The 10-section ASVAB improves the matching of volunteers with available jobs and helps match job openings with qualified individuals.
After adding so much information to the aptitude test, there was a bit of difficulty interpreting the test results. In addition to that, a vast majority of test takers were deemed as being under qualified based on their test results. This is why the percentile change was made. It ensured that a 50% actually correlated with a person doing better than 50% of the test takers. Those revisions have worked hand-in-hand with the preparation of the armed forces.