Picks come in many shapes and sizes. Picks vary from the small jazz pick to the large bass pick. The thickness of the pick often determines its use. A thinner pick (between 0.2 and 0.5 mm) is usually used for strumming or rhythm playing, whereas thicker picks (between 0.7 and 1.5+ mm) are usually used for single-note lines or lead playing. The distinctive guitar sound of Billy Gibbons is attributed to using a quarter or peso as a pick. Similarly, Brian May is known to use a sixpence coin as a pick, while noted 1970s and early 1980s session musician David Persons is known for using old credit cards, cut to the correct size, as plectrums.
I have heard how giving you are in so many respects of music schooling and I must say that I am impressed. You remind me of the pure idealism that we had in starting Apple. If I were young, with time, I'd likely offer to join and help you in your endeavours. Keep making people happy, not just in their own learning, but in the example you set for them. 

You need to place one finger on whatever fret you want to bar and hold it there over all of the strings on that fret. The rest of your fingers will act as the next finger down the line (second finger barring, so third finger will be your main finger, and so on). You can also buy a capo, so that you don't have to deal with the pain of the guitar's strings going against your fingers. The capo bars the frets for you. This also works with a ukulele.
While Courses are a great way to learn guitar on your own, sometimes you need personalized feedback or private lessons from top guitar instructors in order to bust out of that rut or step your guitar playing up to the next level. With no pressure nor scheduling issues, TrueFire Online Classrooms are the best way to take private guitar lessons online!
Adjusting the truss rod affects the intonation of a guitar as well as the height of the strings from the fingerboard, called the action. Some truss rod systems, called double action truss systems, tighten both ways, pushing the neck both forward and backward (standard truss rods can only release to a point beyond which the neck is no longer compressed and pulled backward). The artist and luthier Irving Sloane pointed out, in his book Steel-String Guitar Construction, that truss rods are intended primarily to remedy concave bowing of the neck, but cannot correct a neck with "back bow" or one that has become twisted.[page needed] Classical guitars do not require truss rods, as their nylon strings exert a lower tensile force with lesser potential to cause structural problems. However, their necks are often reinforced with a strip of harder wood, such as an ebony strip that runs down the back of a cedar neck. There is no tension adjustment on this form of reinforcement.
MIDI converters use a hexaphonic guitar signal to determine pitch, duration, attack, and decay characteristics. The MIDI sends the note information to an internal or external sound bank device. The resulting sound closely mimics numerous instruments. The MIDI setup can also let the guitar be used as a game controller (i.e., Rock Band Squier) or as an instructional tool, as with the Fretlight Guitar.
Extending the tunings of violins and cellos, all-fifths tuning offers an expanded range CGDAEB,[25] which however has been impossible to implement on a conventional guitar. All-fifths tuning is used for the lowest five strings of the new standard tuning of Robert Fripp and his former students in Guitar Craft courses; new standard tuning has a high G on its last string CGDAE-G.[26][27]
Guitars have been played since the Renaissance era, after descending from the ancient Greek instrument, the kithara. Or, at least, that's how the theory goes: the only real proof for this is the similarities between the Greek word and the Spanish word, quitarra. Early guitars often had four strings, evolving into the six-string version we know today in the late 1600s. Anton Stradivari, the famous violin-maker, also had a hand in making guitars. There's now only one Stradivarius guitar left in existence.