Rideau Canal National Historic Site of Canada

Locking Through


The principle of water movement in a lock is a very simple one. It is comparable to pulling the plug in your tub, or dumping a glass of water on the floor. The movement of water in both cases is due to gravity. Water runs down hill! This simple notion is applied in the movement of water into and out of a lock. When draining a lock, sluice valves are opened and the water drains out, by gravity. When filling a lock, water flows into the lock again simply by the force of gravity. Nothing pumps water into or out of the lock.


Students will become familiar with the concept of a lock and its anatomy. They learn about the principle of water movement in a lock and visualize how a boat is locked up or down in a lock. Students will work with provided materials to design and build a model lock illustrating the movement of water.

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• Diagram - Anatomy of a Lock
• Diagram - How a Lock Works ( 1, 2, 3 )

Activity 1… Familiarize the students with the anatomy of a lock. Review the basic vocabulary of lock mechanisms (eg. lock, gate, crab, sluice, valve, etc...).

Activity 2… Review the workings of a lock with the students. Have them describe how a lockage works going upstream and/or going downstream.

Activity 3… Ask the students to draw a diagram of a lock and label the parts of a lock.

Activity 4… Have the students draw diagrams of lockages both downstream and upstream. Ask them to provide a written description of the sequence followed when a boat is locked up or down.

Activity 5 Have the students design and build a simple model of a lock.

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