Fix the Program

Free puzzles to print

Each set: a Learn sheet with a worked example, 10 puzzles from easiest to hardest, and the answers.

• Level 2

  Ages 6–8 · Grades 1–2

  

  (arrow cards): first, three programs under one board, and the child checks the one that works. Then one wrong arrow that makes the robot hit a rock or leave the board right where it is. Then a wrong arrow whose effect shows a few cards later, or a missing arrow. The hardest puzzles have an extra arrow, or don't say whether a card is wrong, missing or extra.

  On the sheet: “The robot should stop on the picture. One card is wrong. Cross it out and draw the right card.”

  Print Level 2 (Letter)Other paper size: A4

• Level 3

  Ages 8–10 · Grades 3–4

  

  (turn cards on path-shaped boards): one wrong card, then one missing or one extra card. Then the bad card sits inside a repeat box, so it goes wrong every time the box runs. The hardest puzzles add apples to pick up, and the wrong card sits inside F1, a little named program, while MAIN is right.

  On the sheet: “The robot should stop on the picture. One card is wrong. Cross it out and draw the right card.”

  Print Level 3 (Letter)Other paper size: A4

The thinking it works on

• Finding the first error

  Runs the program until the robot goes off course, then looks there.

  Markman (1979) found that children in grades 3 to 6 often said short essays with plain contradictions made sense. They could recall the facts and draw the inferences, but spotting the problem took a deliberate check they did not make on their own. Source

• Comparing plan and result

  Keeps the goal in mind while watching what the program really does.

• Cause and effect at a distance

  Sees that a wrong card can do its damage later.

  Schlottmann (1999) found that 5- and 7-year-olds expected a cause to be followed at once by its effect. When a bell rang right after a second ball was dropped, they picked that ball as the cause, even when they knew the box worked with a delay. Source

• Checking your own work

  Runs the fixed program again from the start.

  Destan and colleagues (2014) found that 5- to 7-year-olds were more confident in their right answers than their wrong ones. Using that feeling to keep the good answers and drop the bad ones grew stronger with age. Source

• Seeing structure in a program

  Knows that one bad card in a box goes wrong every time the box runs.

  Vourletsis (2026) tested 517 children in grades 1 to 3 on coding ideas and found that questions about loops were harder for them than plain step-by-step sequences. Source

Where is this thinking used?

• Proofreading: Finding the one wrong word that changes a sentence.
• Repairs: Checking each bulb in a string of lights to find the one that's out.
• Baking: Working out which step made the cake sink, so next time only that step changes.
• Programming: Finding and fixing a bug in code by running it step by step.