Solving the light switch puzzle, Mysterious Benedict Society

Key points

• The video's method flips the first switch, waits 10 minutes, then flips the second switch and checks upstairs: a lit bulb means the second switch, while an off bulb is sorted by touch, with hot meaning the first switch and cold meaning the 0:23
• The video presents the second switch as the answer, reasoning that it is the switch by the door, though it admits this rests on a claim about where builders place switches. 0:54
• Three quick ideas are rejected in the video: a very long dental mirror, three spools of twine with a personal dirigible, and flipping the switches repeatedly. 0:14
• In the second test, the floor tiles are each slightly longer than they are wide, so they are rectangles rather than squares, and students who crossed without stepping on a square passed. 2:09
• Christa refuses the next test, calling it impossible and a trick, and the students are sent home. 1:34

The scene, beat by beat

• 1. Rainy's plan — The full method for finding the switch with one trip upstairs. 0:23
• 2. Builder hint — Shows that the answer depends on reading the room's construction. 1:00
• 3. Christa says no — Sets up the second test and the reveal that the tiles are rectangles. 1:13
• 4. Tiles are rectangles — The sign's rule is solved by noticing the tiles are not squares. 2:09

Things worth a closer look

• Watch showing ten minutes — A vintage wristwatch with a brown strap, its hands near the 5 and 30 marks.
• Incandescent bulb on wooden base — A glowing filament bulb mounted on a wooden cylinder and round wooden base.

Questions to check yourself