Run an investigation without guessing the answer
Work through The Mirror Ticket: authenticate a reservation from two observations, explain the waiting reflection, and choose a later sailing when reconstruction uses the available checks.
Put two claims on the table
In The Mirror Ticket, Cera and Noll present apparently identical seat-six tickets. Write two questions: which ticket records the booked journey, and why is a reflection still waiting? At the Mirror-ferry platform, compare the tickets against the light. Ticket A has a physical sun-shaped hole; B only shows its image. Give that observation before asking for an inference. It distinguishes the objects, but it does not yet prove which one the booking clerk should honor.
Combine observations at the booking bay
At the Booking bay, the roll records one seat-six issue for Cera with a sun punch. Pair that record with the material hole before choosing “Authenticate the original with two observations.” Authentication spends one checking interval. Alternatively, the reversible test in the Ticket printroom shows ink on A's fibers and none on B; that observation also combines with the roll. Ask a player to explain why the repeated seat number alone was insufficient. Accept the explanation in their own words.
Solve the display as a separate problem
Visit the Demonstration alcove and read Noll's unfinished log. The mirror was reconnected before its cover step was signed. Combine that sequence with the printroom's image-only result to explain the waiting reflection. Then “Complete the demonstration by covering its pane” costs one checking interval and properly closes the display. Boarding at the gate requires both the authenticated ticket and the completed closure. A correct ticket answer does not automatically finish the reflection's problem.
Make recovery cost something specific
The 90-minute route starts with three checking intervals; the 120-minute route has five. At the Harbor witness desk, retained impressions can reconstruct missing evidence for two intervals. If the short game uses that reconstruction first, only one remains: authentication and covering together would require two. Offer the witnessed later-sailing exchange for the remaining interval, preserving Cera's journey at the cost of delay. With no checks left, suspend the display and protect the reservation. Close by naming the evidence established and the work still unfinished.