Signs that your child loves guitar:

He/she practices every day, even if it if just for five minutes in the morning.
He/she looks up songs on Youtube to learn and play.
He/she is protective of their instrument. Whilst this may create some family conflict, not sharing his/her guitar may be a sign that he/she likes to take care of their instrument; symptoms include wiping down the strings after every practice, or storing it in their special place.
He/she involves YOU in his/her practice - 'Mum, look what I can do!' is one of those phrases that just may make your day!
He/she will practice to a metronome.
They want to show their friends what they can do on guitar.
He/she laughs and smiles when he/she plays.
He/she doesn't have to be told when to practice.

The last point is quite important. Although the above signs are merely instances I have seen whilst teaching, parents' feedback about the final point usually determines if a child would like to continue guitar lessons. Self-driven, independent learning is critical in the early stages of learning an instrument, because it is that foundation of passion and engagement that will drive your child to become the best musician for himself/herself.

Signs that your child has lost interest in playing guitar:

He/she chooses to do something else when she is told to practice.
He/she stops finding songs to listen to.
He/she leaves his guitar in its case, and rarely takes it out to practice.
He/she is grumpy and tired during lessons - although this is hard to read at face value initially, I can tell when a student is disengaged week-by-week and won't be afraid to speak up about it.
During practice, he/she only 'noodles' around - from a musician's perspective, 'noodling' is when one plays guitar only for a brief moment just to play a riff. This usually lasts around 2 minutes before the guitarist drops it to move on to something else. It is preferred that he/she sits down for a block of time to revise techniques and songs learned in the lesson - focus is the key here. This 'noodling' may also point to how your child perceives learning music - if it is on a casual ad-hoc basis, it may be better to consult Youtube or uDemy channels for online lessons and covers.

The "in-between" - frustration during practice

Your child will be frustrated learning guitar throughout their musical development. This is a natural thing to happen to musicians when learning a new technique. As a parent or mentor, you may like to try these few techniques to refocus your child's efforts in music:

Encouragement - this cannot be overstated. A simple 'you sound awesome' can create a push like no other
Separating practice room from bedroom - bedrooms are for sleep and quiet activities. To 'rock and roll' and maintain concentration, a separate room may be better.
Encourage them to take a break during lessons and practices (5 min)
Play everything slow - this may be the root of their frustration, but a slower BPM literally translates to a slower heart rate, allowing for relaxed concentration
Feed them snacks - but not oily foods! Vegetables, seeds and nuts maintain focus the best.
A glass of water on the side always helps

These signs are merely guidelines, and the best way to measure your child's interest in learning guitar is to have a simple direct conversation with them every month. A child's interest in guitar is both self-motivated and influenced by their supporters. A great teacher will know when his student loses focus, and will quickly get them back on track to playing and performing as soon as possible.

Have you noticed your child's interest in guitar declining? What did you do to maintain focus, interest and passion for him/her? Add to the conversation by leaving a comment below.

To confirm: Yes, that is a picture of me playing a guitar in 2005. My first gig too!