The Detective’s DeskAri Lake
Walker
“After three complete crossings I was on the west bank.”
EASY · CASE FILE
The bridge count
Easy · WESTBANK FOOTBRIDGE
Three walkers independently start on the west bank. Each makes only the stated number of complete bridge crossings. There are no boats, other bridges or partial crossings in these accounts.
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.
Your assignment
Inspect, test and record the finding. What does the verified record establish?
- The source records are verified and their stated conditions apply to every account.
- Find the account contradicted by a record. A contradiction alone does not establish wrongdoing.
People and accounts
Basma Ward
Walker
“After two complete crossings I was on the west bank.”
Cal Reed
Walker
“After four complete crossings I was on the west bank.”
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.
NAME REGISTER
The walking-club list
All three walkers belonged to the same club.
All three walkers belonged to the same club.
BRIDGE DIAGRAM
Two banks, one crossing
The bridge joins only the west and east banks. Each complete crossing switches banks. Every walker starts on the west bank.
This is a verified source record for this case. Compare its stated facts with the exact question.
PHOTOGRAPH
The bridge paintwork
The bridge railing was painted blue on both sides.
The bridge railing was painted blue on both sides.
Questions to resolve
Which accounts remain consistent with the verified facts?
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.