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Grade 4 · Machines and Their Mechanisms · Machines and Mechanisms

Trace Motion Through a Machine

A mechanism is a group of moving parts that helps a machine perform a function. Motion and force can change as they pass through those parts.

Visual model

See how the ideas connect

Look · connect · explain
Start at the centre. Follow each line and explain how that idea belongs to Machines and Mechanisms.

For students

Notice, predict, explain

Choose one part of the model. Predict how it connects to another part, then use the lesson evidence to explain your thinking.

For teachers

Pause for science talk

Show the model before the explanation. Ask “What do you notice?” and “What might change?” Then revisit student ideas after the worked example.

The big idea

Mechanisms transmit and transform motion

Gears, belts, chains, cams, and linkages can transfer motion between parts or change its direction, speed, force, or type.

Work it through

Connect a small gear to a large gear

  1. Step 1 Turning the small input gear makes its teeth push the teeth of the larger output gear.
  2. Step 2 Meshed gears rotate in opposite directions.
  3. Step 3 The larger gear completes fewer rotations than the smaller gear, so the output is slower.
  4. Step 4 The slower output can provide a greater turning effect, depending on the complete machine and its losses.