Whether you want to become a professional music teacher, or are simply trying to teach your children to play, there are several important things to understand about the difference between children and adults when starting to play an instrument. The most important rules are: 1) understand that for a child, starting to play the guitar is a demanding process and that it is therefore up to you to try to do everything possible to facilitate this experience; 2) understand that for him it can be frustrating and boring, and therefore you should try to do everything possible to make this experience fun.
Steps
Step 1. Help him choose the right tool
There are guitars of various shapes and sizes, and choosing which one to buy first can be difficult. Try not to make him spend a lot. It is important to remember that he will have to change the first instrument after a year or so and, by that time, the child will surely have a clearer idea of what is best for him. But try not to recommend a guitar that is too cheap or poor: it will also be more difficult to play. The most important selection criteria are: is the guitar easy to pick up? Is it easy to play? Try to get him to buy a custom-made, child-sized guitar with nylon or steel strings.
Step 2. Make him friends with the guitar
Instead of a reverential approach to learning one thing at a time, invite him to experiment with freedom of expression from day one. For example, you might try inviting him to keep the beat on the guitar itself. Push him to accompany you as you play on his "percussion guitar". The best way to do this is to wrap a piece of cloth around the neck of the guitar to mute the strings, then let the child try to strum with his right hand. Encourage him to vary the modality, tempo, and complexity of the rhythm.
Step 3. Help him tune the guitar
It is not advisable to teach him how to tune the guitar right away: for the first few times, it is better for an adult to make sure that the guitar is tuned and ready for the lesson. Ask the child if there is anyone at home who can help him tune the guitar. For the little ones, learning this process is quite difficult. Of course, sooner or later he will have to figure out how to do it, but in the beginning it is much more important to make this process as easy as possible. Cheat a little and get yourself an easy-to-use tuner, then patiently explain to your child how to use it.
Step 4. Start with the simplest things
You could start with the James Bond theme and divide it into three parts, or use the riffs of Seven Nation Army (White Stripes), Sunshine of Your Love (Cream), Another One Bites the Dust (Queen), Smoke on the Water (Deep Purple) and other songs you like. All very famous, simple and easy to play (below you can find links to the scores and sound files for some of these proposals).
Step 5. Repeat, repeat, repeat
Repetition is an integral part of the learning process, and luckily, children are often happy to play the same thing over and over again. Encourage them and resist the (very adult) urge to push them to try new things. Remember that when a child says he likes a certain melody, it almost always means he thinks he can play it well. Conversely, when a child states that he doesn't like a particular melody, it may mean that he finds it too difficult, at least for the moment.
Step 6. Work against the clock to improve the speed of the chords
To teach your child how to make chords the right way, you can choose a pair such as "a" and "king" and ask him to show you how many times he can change chords in one minute. Start a stopwatch and have it try. Pause to give him some suggestions on how to make the change easier (move your fingers in the same order, feel where the strings are without looking) and then have him try again to see if he beats his personal best.
Step 7. Simplify the agreements
If the child wants to learn a specific melody, but the chords are too difficult for his current abilities, try to simplify them. You can change a note, use a different nut, or devise a way to place your fingers on three strings instead of four, five or six. It is a process that requires some musical skill, but in this way you can do some practice too!
Step 8. At first try to find out if the child prefers to play chords or single notes
Some prefer to play melodies, while others throw themselves headlong into chords. Find out what they find simpler and more fun and continue on this path! As they grow in height and capacity, you will be able to address the other issues that you may have overlooked at the beginning. There is no rush: don't worry about doing everything from the beginning.
Step 9. Don't bother teaching him the theory right away
It makes no sense to confuse the child by introducing too complex theoretical concepts right away. Don't even try to simplify the topic. It is possible that the children have learned some basic notions since elementary school (such as the names of the notes or concepts such as clef and scale). In this case, you can always refer to the notions already learned at the appropriate time. Don't just focus on theory, although deepening your lessons with a few theoretical notions every now and then could be fruitful.
Step 10. Encourage practice, but be careful not to make it a requirement
In the beginning, you will get the best results with short practice sections, rather than through prolonged workouts. Practicing little and often is the key to learning.
Step 11. Encourage them to sing
Singing while playing is natural for a child, and doing so has several benefits. At first it may seem like an excessive workload and you may think you are penalizing his ability to reproduce chords, since the child could inevitably concentrate more on singing; however, as he practices, things will settle down: just bring a little patience.
