PAPER PRACTICE

Cross Lights: Predict a press before making it

Three fixed studies, followed by separate answer pages. The links and IDs match the online collection.

Switch every light off. Pressing a square flips that square and its horizontal and vertical neighbours. Edges do not wrap and diagonals do not change. The fixed challenges stop when solved. The prediction drills describe toggle operations even when an intermediate pattern is dark.

Use your browser’s Print command or Save as PDF. Both A4 and US Letter fit the diagrams. To keep answers separate, print only the challenge pages. The answer pages contain two useful checkpoints; the online practice page contains the complete checked route.

Return to the online collection

CHALLENGE 1

Cross Lights study 1

ID: lights-01 · Board: cross-study-1

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Explain one move you can prove. Which displayed clue or rule supports it?

Reason: ____________________________________________________

___________________________________________________________

playfieldarcade.com/practice/lights/lights-01/ · Personal, family and classroom printing permitted.

CHALLENGE 2

Cross Lights study 2

ID: lights-02 · Board: cross-study-2

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Explain one move you can prove. Which displayed clue or rule supports it?

Reason: ____________________________________________________

___________________________________________________________

playfieldarcade.com/practice/lights/lights-02/ · Personal, family and classroom printing permitted.

CHALLENGE 3

Cross Lights study 3

ID: lights-03 · Board: cross-study-3

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Explain one move you can prove. Which displayed clue or rule supports it?

Reason: ____________________________________________________

___________________________________________________________

playfieldarcade.com/practice/lights/lights-03/ · Personal, family and classroom printing permitted.

ANSWER 1

Cross Lights study 1

ID: lights-01 · Board: cross-study-1

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Two checkpoints in the solution

Testing all 32 possible first-row patterns and chasing downward gives a valid plan from this exact position: R1C1. Press R1C1 first; it toggles R1C1, R2C1, R1C2. This is one working plan, not a claim of fewest moves.

playfieldarcade.com/practice/lights/lights-01/ · Personal, family and classroom printing permitted.

ANSWER 2

Cross Lights study 2

ID: lights-02 · Board: cross-study-2

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Two checkpoints in the solution

Testing all 32 possible first-row patterns and chasing downward gives a valid plan from this exact position: R3C3. Press R3C3 first; it toggles R3C3, R2C3, R4C3, R3C2, R3C4. This is one working plan, not a claim of fewest moves.

playfieldarcade.com/practice/lights/lights-02/ · Personal, family and classroom printing permitted.

ANSWER 3

Cross Lights study 3

ID: lights-03 · Board: cross-study-3

Cross presses toggle side neighbours; ● on, ○ off
	C1	C2	C3	C4	C5
R1
R2
R3
R4
R5

Two checkpoints in the solution

Testing all 32 possible first-row patterns and chasing downward gives a valid plan from this exact position: R1C1, R5C5. Press R1C1 first; it toggles R1C1, R2C1, R1C2. This is one working plan, not a claim of fewest moves.
Testing all 32 possible first-row patterns and chasing downward gives a valid plan from this exact position: R5C5. Press R5C5 first; it toggles R5C5, R4C5, R5C4. This is one working plan, not a claim of fewest moves.

playfieldarcade.com/practice/lights/lights-03/ · Personal, family and classroom printing permitted.