The Detective’s DeskRana Cole
Club leader
What happened from your point of view?
The pump was on when I left.
What should I check to test that account?
Tess had been told it must stay on during the inspection.
EASY · CASE FILE
Who Turned Off the Tank?
Easy · A school aquarium club
The air pump is found off. Follow its plug and the switch settings, then distinguish a cleaning job from a deliberate change.
Read the case file below, or open the interactive desk to examine records, keep notes and submit your reasoning. These are the case materials, without the solution.
The scene
The fish are safe in a spare tank. A clear maintenance sheet explains the equipment; no aquarium knowledge is required.
People and accounts
Mika North
Cleaner
What happened from your point of view?
I unplugged the separate desk fan as asked.
What should I check to test that account?
The fan uses socket C.
Tess Lake
Display helper
What happened from your point of view?
I switched off only the empty display lamp.
What should I check to test that account?
I used socket B, the one marked pump.
Case records
Read each record on its own terms. A claim made by a person is different from a fact established by an independent record.
Case record · Equipment bench
Socket map
Pump is on B, lamp on A, fan on C. Each cable is traced end to end in the supplied check.
Case record · Tank corner
Cleaner’s task receipt
Mika’s receipt names fan C only. Its unplugged cable matches the fan, not the pump.
Case record · Equipment bench
Tess’s signed task note
Tess acknowledges “leave pump B on”; underneath she writes “turned B off so inspection would fail”.
Case record · Tank corner
Switch seal
The dated paper seal on B is cut; B is off. A is still on and C is unplugged.
Questions to resolve
Who records intentionally disabling the pump?
Which action belongs to the cleaner’s documented task?
Use the interactive case desk to select your finding and cite the records that support it. The answer is checked there, and your progress stays in your browser.
Build your finding
Compare the records with each account. Work out what the evidence establishes, then separate that finding from anything it does not prove.