For Teacher Reference
TOP ROW: x, y solution
MIDDLE ROW: letters of the message
BOTTOM ROW: position number-only line put on the board
13 | 1 | 20 | 8 | 9 | 19 | 14 | 15 | 20 | 1 | ||||||||
M | A | T | H |   | I | S | N | O | T | A | |||||||
1 | 2 | 3 | 4 | 5 |
19 | 16 | 5 | 3 | 20 | 1 | 20 | 15 | 18 | 19 | ||||||||
S | P | E | C | T | A | T | O | R | S | ||||||||
6 | 7 | 8 | 9 | 10 |
16 | 15 | 18 | 20 | ||
P | O |   | R | T |
On the board:
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1 2 3 4 5
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6 7 8 9 10
_________________________________________________
11 12