Suns & Moons

Free puzzles to print

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

• Level 1

  Ages 4–6 · Pre-K–K

  

  4 × 4 grids with most squares already filled, then fewer filled, then 6 × 6 with many filled. Spotting pairs and gaps finishes each one, with no counting needed.

  On the sheet: “Same number of suns and moons in each row and column. Never three alike in a line.”

  Print Level 1 (Letter)Other paper size: A4

• Level 2

  Ages 6–8 · Grades 1–2

  

  4 × 4, then 6 × 6, then 6 × 6 with fewer given. Counting what a line still needs starts here.

  On the sheet: “Same number of suns and moons in each row and column. Never three alike in a line.”

  Print Level 2 (Letter)Other paper size: A4

• Level 3

  Ages 8–10 · Grades 3–4

  

  8 × 8; the hardest puzzles need a check across the whole line.

  On the sheet: “Same number of suns and moons in each row and column. Never three alike in a line.”

  Print Level 3 (Letter)Other paper size: A4

• Level 4

  Ages 10–12 · Grades 5–6

  

  A new rule (no two rows or columns the same), then 10 × 10, with one "what if" in the hardest puzzles.

  On the sheet: “Equal suns and moons in each row and column. Never three alike. No two rows or columns match.”

  Print Level 4 (Letter)Other paper size: A4

The thinking it works on

• Applying a rule the same way every time

  Scans for two alike side by side, or a gap between two alike, and applies the rule.

• Reasoning by elimination

  Uses 'not a sun, so a moon' many times per grid.

  Mody and Carey (2016) found that 2½-year-olds did not yet reason by elimination between two hiding places, while 3- to 5-year-olds did. Source

• Counting what is left in a line

  Counts a line and fills the rest once half is placed.

  Across children aged 4 to 15, Gathercole and colleagues (2004) found broadly similar straight-line rises with age on every working memory measure they used. Source

• Checking rows and columns together

  Looks along the row and the column after every mark.

  Battista and colleagues (1998) found that the row-by-column layout of a square grid, which adults take as obvious, is something many students have not yet built. Source

• Checking the whole line before guessing

  Checks whether the rest of a line could still work before marking a square.

  Roebers (2017) reviews research showing that self-control and the habit of watching over one's own thinking both develop steadily through childhood. Source

• Testing a 'what if'

  Supposes a sun, follows it, and switches to a moon if a rule breaks.

  Moshman and Franks (1986) found that fourth graders judged arguments by whether the facts were true, while many seventh graders judged whether the conclusion followed. Source

Where is this thinking used?

• Schedules: Every slot has limits, and one choice changes the others.
• Fair halves: Balancing teams or turns half and half.
• Checking changes: A change in one place must not break something elsewhere.