Key learning points

1. Not all real-life graphs can be drawn using sections of different linear graphs.
2. The graphs are models, which means that we want them to be useful.
3. Different containers may need different graphs to model filling them.
4. Volume of liquid changes over time and this is affected by container shape.

Common misconception

Keywords

• Time series graphs - Time series graphs show data over a time period. The time period is always shown on the $$x$$-axis. Data points are joined chronologically by line segments.

• Extrapolation - Extrapolation is the process of estimating unknown values that are outside the range of existing data.

• Interpolation - Interpolation is the process of estimating unknown values that are inside the range of existing data.