Understanding Movement Along the Demand Curve vs. Shift in Demand

This lesson explores the difference between movement along the demand curve and a shift in the demand curve. A movement along the curve occurs when the price of the good changes, causing a change in the quantity demanded. A shift in demand occurs when factors other than the good's own price change, such as consumer income, tastes, or the prices of related goods. The graph uses the demand equation P = a − 2Q, where Price is on the vertical axis and Quantity is on the horizontal axis. The intercept a represents the position of the demand curve.

How to Use the Playground

• Drag the dot to move along the current demand curve, changing Price and Quantity together.
• Use the Price controls ( slider, or +/− buttons (on mobile)) to move along the demand curve.
• Use the Demand Intercept controls to shift the entire demand curve left or right.
• Observe how changing Price causes a movement along the curve, while changing the intercept creates a shift in demand.