Or search by topic
There is a circular railway siding at the end of the main line.
C is a cattle truck,
S is a sheep truck,
E is an engine.
The engine can pass under the Foot Bridge but the two trucks cannot because they are too tall. The problem is to shunt the trucks so that the Cattle truck and the Sheep truck change places and the Engine is back on the main line.
This practical challenge invites you to investigate the different squares you can make on a square geoboard or pegboard.