Two-load courier
Plan pickup and delivery under a two-parcel carrying limit.
Logic & rule checking
- Players
- 1–4 cooperatively
- Time
- 12–20 minutes
- Materials
- Ring map A–B–C–D–A, courier marker and three parcel cards.
Prepare
Draw the undirected ring AB,BC,CD,DA, each edge costing one move; there are no diagonal shortcuts. Start the courier at A with no cargo. Parcel P is waiting at A for C, Q at B for D and R at C for A. One team shares the courier and one move ledger.
Play
At your current node, pick up or deliver any eligible parcel for free, but never carry more than two. A parcel cannot be delivered at the wrong destination or loaded before the courier reaches its origin. Moving along one drawn edge costs one. Leave uncollected parcels at their origin; delivered parcels stay delivered.
Worked example
Load P at A. Move to B and load Q: two aboard. At C deliver P and load R, leaving Q and R aboard. At D deliver Q; return to A and deliver R. The route A–B–C–D–A costs four moves and respects capacity at every point.
Finish and check
Complete all three deliveries and finish at A. Compare routes only after checking the cargo log. The supplied four-move route is minimal on this ring because a closed walk visiting all four nodes cannot use fewer than four edges. A different map needs its own argument. Stop at completion or twelve moves.
Adaptation and limits
Rotate planner, courier mover and cargo checker after each leg. Use letters and parcel IDs, not colour alone. No timed handoff or real address is needed. For a new challenge change one origin or destination publicly before resetting every parcel, then write a fresh checked route.
Purpose, observation and provenance
Within this activity: Plan pickup and delivery under a two-parcel carrying limit.
Explain one legal decision and check it against the written constraints; a single result does not measure lasting ability.
Our rules, examples and printable diagrams are separately prepared. The earliest inventor of the broader mechanism is not established here.
Free alternative: Copy the supplied grids, labels and cards onto reused paper. No specialist product is needed. Adults may prepare pieces or act as a scribe.
Printable materials
Preview at 100% scale, with browser headers and footers off. Cut with suitable help. Keep host keys separate. This is a manual tabletop kit, not an online opponent, automatic judge or solver.
Player materials · Two-load courier
P A→C; Q B→D; R C→A. Carry≤2.
Move / node / load / delivered / cargo count.
Player record · keep host key separate
| Move/node | Picked up | Delivered | Aboard |
|---|---|---|---|
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
Host key · separate from players
A(loadP)→B(loadQ)→C(deliverP,loadR)→D(deliverQ)→A(deliverR), four paid moves.
Run the round
Draw the undirected ring AB,BC,CD,DA, each edge costing one move; there are no diagonal shortcuts. Start the courier at A with no cargo. Parcel P is waiting at A for C, Q at B for D and R at C for A. One team shares the courier and one move ledger.
At your current node, pick up or deliver any eligible parcel for free, but never carry more than two. A parcel cannot be delivered at the wrong destination or loaded before the courier reaches its origin. Moving along one drawn edge costs one. Leave uncollected parcels at their origin; delivered parcels stay delivered.
Load P at A. Move to B and load Q: two aboard. At C deliver P and load R, leaving Q and R aboard. At D deliver Q; return to A and deliver R. The route A–B–C–D–A costs four moves and respects capacity at every point.
Complete all three deliveries and finish at A. Compare routes only after checking the cargo log. The supplied four-move route is minimal on this ring because a closed walk visiting all four nodes cannot use fewer than four edges. A different map needs its own argument. Stop at completion or twelve moves.
Rotate planner, courier mover and cargo checker after each leg. Use letters and parcel IDs, not colour alone. No timed handoff or real address is needed. For a new challenge change one origin or destination publicly before resetting every parcel, then write a fresh checked route.
Related activities
Activity library · Weighted bridge network: rules and printable materials