The No-Nonsense Technician Class License Study Guide is the quickest way to get your license. It clearly and succinctly explains the concepts, while at the same time, give you the answers to all of the questions that you'll find on the test.
Here's an example:
Voltage is the force that causes electrons to flow in a circuit. Voltage is sometimes called electromotive force, or EMF. Voltage is the electrical term for the electromotive force (EMF) that causes electron flow. (T5A05) The volt is the basic unit of electromotive force. (T5A11) The letter V is shorthand for volts.
You use a voltmeter to measure electric potential or electromotive force. (T7D01) About 12 volts is the amount of voltage that a mobile transceiver usually requires. (T5A06)
Read through the study guide a couple of times, take some practice tests online, and you'll be ready for the test in no time!