2100 puzzle rating but a 600 rapid rating?!?
That is pretty normal in my opinion. A lot of the players who I have seen have puzzle ratings which are significantly higher than their game ratings.
Puzzles train us to spot tactics and play defensive moves, and it is a subset of all the entire aspects of chess. Unfortunately, in puzzles, we know that there is a winning line (or a drawing line, in the case of averting a loss) to pursue, so all we need to do is to make calculations.
In actual games, however, there are other important areas to consider, such as the opening phase, the development phase, the middlegame phase and the endgame phase. In most circumstances, the actual tactical ideas do not exist upfront. There might not be even any particular tactic present. One might be tempted to attempt a tactic which could eventually backfire.
More often that not, however, the tactics which a player has learnt serve to achieve two purposes.
- Provide recognition to similar situations. Notwithstanding what I wrote above, errors and blunders do happen from time to time, and if a good player notices it, he can pounce on the error by using a tactical idea from puzzle training or otherwise.
- Defend against opponents' potential tactics. This is less commonly observed, but plays a vital role in maintaining one's position. An awareness of the potential tactics played against a player will allow him to avert the disaster of handing the advantage down to his opponent.
There are certain considerations for a rapid rating of 600.
- Does he start his Chess.com account with a "high rating" which is not really accurate? Starting ratings are not reflective of one's actual game plays, so if he starts with a rating of, say, 1200, he must be prepared that 1200 may not be his true rating. If he eventually drops to 600, he cannot say that "I was once a 1200 rated player" as his rating becomes stable at 600.
- Does he take time to play moves? Or does he make moves rashly without realising the potential responses by the opponent?
- Is he prone to blunders and hanging pieces? Or does he regularly miss hanging pieces and tactics which could have bagged him the winning games?
- Does he have real-life classmates/peers/relatives who regularly play chess?
- Does he regularly watch chess videos, analyse his losses, seek opinions from more advanced chess players etc? Or does he follow the games of more advanced players eg a 1600 vs a 1600? (I won't recommend the games of grandmasters at this point as the underlying ideas are too deep for many players in the rating range under 1000)
I have no idea why it is… But skill at solving tactics puzzles has almost nothing to do with playing good chess. On the flip-side, I see people all the time with a rapid rating over 2000 who can’t break 2500 in tactics. So there are obviously a lot of other skills the have that are paying off in rated play.
Thank you all for responding. It makes more sense now. I guess I should direct his time to other areas of chess and less puzzles then. He also moves too quickly without thinking of a strategy. He watches Hikaru and gets motivated to play fast like him but it doesn’t work out too well for him. He likes chess so much and can play for many hours even all day. Maybe I should invest in a coach/ tutor once or twice a week to help him. His 10 yr old friend and him were winning tournaments here in Colorado. His friend is now 1600uscf and my son is trying really hard to beat him in state championship this year
I’ve spent like 50:1 time on puzzles vs playing. And it actually turned me into a moron in my games.

xfallesafe is right I have done a few puzzles but I ended up stopping due to the fact that they are just complete wastes of time my chess skills did not improve as a result of using them so to a chess noob I would recommend analysing your games and what you may have done wrong rather than solve something with a randomised order of chess pieces that probably won't appear in any of your games.

I may be repeating what others have said, but puzzles always have a "right" answer. You know a tactic is there that either wins the game or gains a large amount of material (a full piece or more). Often it involves a sacrifice. When I do puzzles I look for these things, but it doesn't really help my game. In a live game there could be more than one right answer, or no right answer. A win could be within reach or you could be dead lost, the only way to know is to carefully evaluate the position, something the puzzles do not teach you.
And nearly everyone has a puzzle rating much higher than their chess rating. My peak puzzle rating was over 1800 but my live chess is rated barely 1000. Your son's situation is perfectly normal.
xfallesafe is right I have done a few puzzles but I ended up stopping due to the fact that they are just complete wastes of time my chess skills did not improve as a result of using them so to a chess noob I would recommend analysing your games and what you may have done wrong rather than solve something with a randomised order of chess pieces that probably won't appear in any of your games.
Playing and analyzing your games are great, but don’t discount solving puzzles. Puzzles assist with several things, evaluating positions and pattern recognition. Both will spill into your games and over time improve your play tremendously. However puzzle solving can be less effective when you skip the evaluating the board to understand what’s going on and just guess the first thing you see. I recommend continuing to solve at least a few puzzles each day, even if just as a warm up before playing a game.
As for the 2100 puzzle rating and 600 game rating, puzzle ratings are generally inflated, can easily be manipulated in multiple ways, and can be misused such as noted above. It sounds like there’s several issues, such as time management, that’s affecting the kids gameplay.
-Jordan
xfallesafe is right I have done a few puzzles but I ended up stopping due to the fact that they are just complete wastes of time my chess skills did not improve as a result of using them so to a chess noob I would recommend analysing your games and what you may have done wrong rather than solve something with a randomised order of chess pieces that probably won't appear in any of your games.
But for how long did you spend puzzles on? If it's just a week or two, it's definitely not long enough. You need to embark on a longer time frame.
But if it's half a year and you still have a similar issue, then it's probably some difficulty retaining patterns or looking out for opportunities in actual games.

I'm in the same boat but a little higher in rating (~1150 rapid now). I can tell you what I started doing that has netted me games in the 90+ accuracy range.
#1 - Only G30s and nothing faster. This depends a lot on your ability to calculate lines quickly and see certain ideas present on the map (not only easy things like pins, but is a support piece being pinned and there's a tactic for the opponent? What about double checks, discovered attacks, removing the defender ideas...?, etc.) Assuming he's playing fast, he should take all the time he needs. I recently finished a ~95% accuracy game, 40+ moves, using all my time. My opponent had 10+ mins left on his clock. As you can see, taking all the time, seeing everything on the map, and making your smartest decision will help a lot.
#2 - Speak out loud what you are seeing. He can talk to you, someone else, or just himself; it doesn't matter. The idea is to verbalize what you're seeing and follow a basic checklist at times.
#3 - There are some checklists out there. The most basic one he needs to start doing on every move, even opening moves, are these:
Step 1. How did my opponent's last move affect the position? Is he threatening anything (meaning, is he attacking something undefended)? If yes, move on to step 1a. If not, move on to step 2.
Step 1a. Do I need to defend (move or support depending on the value), or should I make a stronger threat (Yes, my knight is hanging, but your Queen is trapped when I move my Bishop there, go ahead, take it!).
Step 2. Did my opponent leave anything hanging? If so, and a quick tactics check pans out, go ahead and take it! It's free! Remember to check if taking it will make you lose out on more material (take his free Bishop, but he can get your Queen, yikes!). These are the traps and gambits in the e4 c5 lines. Cheeky stuff. Never assume it's free because they forgot about it (which will be the case the lower you go).
Step 3. Calculate tactical lines, especially when Kings are open to attack or there is tension between pieces (Bishops defended by pawns are looking at each other. That's fine, but after I go first and we trade, your Knight is hanging, and my Queen takes it for free. 600's aren't noticing these 1-2 move calculation ideas). Calculate the opponent's lines as well. This takes time and is slow to improve, that's why G30s are my minimum for now.
Step 3. If nothing "juicy" is on the board, ask yourself: Is my next potential move following Chess Principles? Attacking the center, casting early, Rooks on open files, leaving no piece hanging, moving my pieces toward the enemy king, improving my worst placed piece, developing rapidly without blundering to tactics, etc.). Never rely on "hope chess," which is seeing a cheeky tactic working if your opponent doesn't notice it. For example, don't put your Knight on a4 hoping he didn't see it attacking his Queen on b6 after a discovered check; he'll just move it to safety (or threaten something else!). This may work a fair amount of time in the lower ratings, but it should be reserved for those who are "just having fun" and don't care about improving into the higher ratings (faster games utilize these tactics well too). Make sure your moves are almost always positionally sound by following chess principles.
5. Finally, commit to the move and start thinking about what the opponent can do in response. While it's their turn to move, you should be formulating responses to their potential responses. This will make your response quicker in turn.
Let me know if this helps! I'm sure it will!
P.S. - If anyone higher rated wants to touch on this "low elo" check list, I'd love to see it!
P.P.S. - I used "he" as the pronoun for easier reading. Obviously, this applies to any other player present!
Have a great day!

Just tell him to play longer games, and revisit these games in analysis
Some time has passed since this publication was made, but I think it has been very little and some advice can still be useful.
It is not good to focus so much on the rating, you have to focus more on improving the different aspects of the game; For example, there are 1500 elo players who only play against the clock and don't really have much of an idea of what they're doing, others are just slower but have a more coherent game; In both cases there are people of 1500 elo, but in reality one group is just dropping pieces for pranks or winning victory points by playing for time, while the other group is concentrating more on the quality of their game and not just on the game. time; In the long term the second group should increase in rating, while those desperate simply for some pleasant victories are mostly destined to get stuck.
It would be necessary to see what the problem is with his rating in rapids, but it is very likely that if he plays rapids he does not consume his time and his games end up in completely lost positions without having spent the vast majority of his time. He has to understand that learning is a process and also let him know that he needs to play slow games if he wants to progress as a player. The important thing is that you play to improve, the rest are just numbers that reflect the results and you should not despair of those numbers.
Work your weak points, but also your strong points;
If he is better at solving tactical problems, look for tactical training books for children and then look for more and more books for his level as his tactical abilities improve, it is also good for him to receive some calculus training; If he really likes puzzles, it is very possible that it motivates him more.
Obviously he will need to see his defects and why he is doing badly in his games, for that it would be good for a coach to review the child's game history.
xfallesafe is right I have done a few puzzles but I ended up stopping due to the fact that they are just complete wastes of time my chess skills did not improve as a result of using them so to a chess noob I would recommend analysing your games and what you may have done wrong rather than solve something with a randomised order of chess pieces that probably won't appear in any of your games.
The idea is not that the position is repeated exactly the same, it is to learn to detect tactical patterns and take advantage of these details in different positions and stages of the game.