The Armed Forces Tuition Assistance (TA) Program allows enlisted servicemembers and offers to enroll in courses at accredited colleges, universities, junior colleges, high schools, and vocational-technical schools. TA will pay up to 100% of the cost of the course and up to 100% of the cost of obtaining a high school degree, with a limit of $250 per credit hour and an aggregate annual limit of $4,500. MGIB benefits may be used to "top up" TA benefits, paying the difference between tuition and the TA benefits. provides a good overview of the tuition assistance program.
Each service has a uniformed head who is considered the highest-ranking officer within their respective service, with the exception of the chairman and vice chairman of the Joint Chiefs of Staff, and the chief of the National Guard Bureau. They are responsible for ensuring personnel readiness, policy, planning and training and equipping their respective military services for the combatant commanders to utilize. They also serve as senior military advisors to the President, the Secretary of Defense, their respective service secretaries, as well as other councils they may be called to serve on. They are as follows:
Arguably, the greatest invention that affected not just the military, but all society, after adoption of fire, was the wheel, and its use in the construction of the chariot. There were no advances in military technology, until, from the mechanical arm action of a slinger, the Greeks, Egyptians, Romans, Persians, Chinese, etc., development the siege engines. The bow was manufactured in increasingly larger and more powerful versions, to increase both the weapon range, and armour penetration performance. These developed into the powerful composite and recurve bows, and crossbows of Ancient China. These proved particularly useful during the rise of cavalry, as horsemen encased in ever-more sophisticated armour came to dominate the battlefield.

The IRT model underlying ASVAB scoring is the three-parameter logistic (3PL) model. The 3PL model represents the probability that an examinee at a given level of ability will respond correctly to an individual item with given characteristics. Specifically, the item characteristics represented in the 3PL model are difficulty, discrimination (i.e., how well the item discriminates among examinees of differing levels of ability), and guessing (i.e., the likelihood that a very low ability examinee would respond correctly simply by guessing).