I Tested 885 Duolingo Chess Puzzles. 24% Do Not Make Sense.

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I Tested 885 Duolingo Chess Puzzles. 24% Do Not Make Sense.<br>Thousands of beginners are failing puzzles that were never solvable.

Tyler Schwartz<br>Jul 13, 2026

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Oscar told me to ignore his rook on c1.<br>There is no rook on c1.

Oscar, buddy. I’ve stared at this board for five minutes. I’ve counted my rooks. I even considered that maybe, from Oscar’s side of the board, some other square was secretly c1. There is no universe in which I have a rook on c1.<br>The more I did Duolingo Chess, the more issues I noticed.<br>Share<br>Hi, I’m Tyler

I’m a chess nerd, professionally. My first job out of college was teaching chess in a preschool. I turned my method into a company, Story Time Chess, which won Toy of the Year in 2021 and 2025. I once beat US Chess Champion Hikaru Nakamura, which I mention at every possible opportunity. I will mention it three more times in this blog. Consider yourself warned.<br>So when Duolingo, one of the biggest education companies on Earth, launched a chess course in June 2025, I was thrilled. Teaching chess to total beginners is my life’s work, and now the biggest name in learning apps was going to do it at a scale I could only dream about. I dove in immediately.<br>And a lot of it is great. The gamification is excellent, the pacing between lessons feels right, and some of the puzzles are so good I screenshotted them just to admire them later.<br>But, I kept hitting puzzles that felt... off. Lessons that didn’t teach what their titles promised. Solutions a beginner couldn’t reasonably find. And Oscar confidently describing pieces that did not exist.<br>I wanted to investigate further. Did I mention, I love doing chess puzzles?<br>What I Did

I went through Section 7 of Duolingo Chess, all 885 puzzles, one by one, and evaluated each on two questions:<br>Does the puzzle teach what it claims to teach? If the lesson says “Skewers,” is a skewer actually the point of the solution?

Could a beginner realistically solve it? Duolingo’s audience isn’t tournament players. It’s people learning chess on the bus.

I sorted every puzzle into Effective, Not Effective, or Borderline. When a puzzle didn’t work, I coded why, using a rubric of 14 issue types I built as patterns emerged. Every puzzle got a difficulty rating and an expected success rate. Yes, there’s a spreadsheet. Yes, it has multiple tabs. I told you I was a nerd.<br>What I Found

672 (76%) are effective . Three out of four puzzles do their job.

178 (20%) are not effective.

35 (4%) are borderline.

That’s 213 puzzles, 24% of the section, with problems.<br>Now the painful part. Let’s do some math. Duolingo reports 7 million daily active chess users. Assume just 10% of them are in Section 7 on any given day, it’s the final section, where every learner eventually lands and stays. That’s 700,000 people. Say each one does a modest 10 puzzles a day. That’s 7 million Section 7 puzzles served daily, and if 24% have problems, that’s roughly 1.7 million broken puzzles handed to unsuspecting beginners. Per day. Over 600 million a year, from one section of one course. Cut my assumptions in half if you like. It’s still 400,000 a day.<br>What is wrong with these puzzles? I coded 181 issues across those puzzles, spanning 14 issue types, and just two issue types account for nearly two-thirds of everything wrong.

That’s not 181 random problems. That’s two problems, repeating. And that’s great news, because two problems can be fixed.<br>Problem One, Theme Not Present: The Lesson Doesn’t Teach What the Label Says

Imagine a Where’s Waldo book where, on some of the pages, Waldo just isn’t there. Nobody tells you this. You search the beach scene for twenty minutes. You check every stripe, every hat. Nothing.<br>Here’s the sad consequence: you don’t conclude the book is defective. You conclude you’re bad at finding Waldo. A kid will sit there feeling dumber and dumber, hunting for a man who was never on the page.<br>That’s Theme Not Present, and it happens 60 times in Section 7. Duolingo tells you to find the fork, and there’s no fork on the page.<br>My favorite example is from a lesson called “Disadvantage Promotions.” (I’ve taught chess for over a decade and have never heard this term, but let’s roll with it.) Oscar tells you to try to promote a pawn. Small problem: White doesn’t have a single pawn past the third rank. Oscar, do you know how pawns move?

The actual solution is a queen sacrifice that sets up a knight fork. It’s a great puzzle! It’s just filed in the wrong drawer. Promotion never happens, never threatens to happen, and was never the point.<br>For the chess players: 1.Qxe7 Qxe7 2.Ng6+ Kh7 3.Nxe7 winning a piece. A clean attraction-into-fork combo. Not a pawn promotion in sight.<br>Problem Two, Branching Variations: Puzzles a Beginner Cannot Actually Solve

Good beginner puzzles run on forcing moves. I check you, you must respond. I take your piece, you must take back.<br>A Branching Variation puzzle has quiet...