Teaching LinkedIn Queens #808: start with region scans on this 9×9 board. 9 regions, sizes 2–39. Walk students through 9 placements ending at R1C6, R2C8, R3C5, R4C7, R5C9, R6C2, R7C4, R8C1, R9C3.
Board spotlight: Several color regions span only a few cells — scan those regions first because they often force a queen into a single row or column. Region sizes range from 2 to 39 cells — smaller regions often pin a queen to a single row intersection.
Lesson step 1: show why R1C6 is forced. Region 4 only touches row 1 once on this board, so its queen must land at column 6. Ask: which rows/columns/regions are now closed?
Lesson step 2: show why R2C8 is forced. Row 2, column 8 is the forced queen once region 1, row, column, and touch rules are applied together. Ask: which rows/columns/regions are now closed?
Lesson step 3: show why R3C5 is forced. Region 3 only touches row 3 once on this board, so its queen must land at column 5. Ask: which rows/columns/regions are now closed?
Lesson step 4: show why R4C7 is forced. Column 7 is the only column still available for a queen in row 4. Ask: which rows/columns/regions are now closed?
Lesson step 5: show why R5C9 is forced. Region 6 only touches row 5 once on this board, so its queen must land at column 9. Ask: which rows/columns/regions are now closed?
Lesson step 6: show why R6C2 is forced. Row 6, column 2 is the forced queen once region 7, row, column, and touch rules are applied together. Ask: which rows/columns/regions are now closed?
Lesson step 7: show why R7C4 is forced. After eliminations, row 7 has one legal square left — column 4. Ask: which rows/columns/regions are now closed?
Lesson step 8: show why R8C1 is forced. Region 5 only touches row 8 once on this board, so its queen must land at column 1. Ask: which rows/columns/regions are now closed?
Lesson step 9: show why R9C3 is forced. After eliminations, row 9 has one legal square left — column 3. Ask: which rows/columns/regions are now closed?
Recap: 9 queens, 9 regions, one solution path. Replay using region-first scanning.