# Lesson Plan: Instantaneous Speed Physics

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to determine the instantaneous speed of an object by using a tangent to find the gradient at a point on the object’s displacement–time graph.

#### Objectives

Students will be able to

- identify from straight-line displacement–time graphs what the speed of an object at a particular instant in time is (as opposed to over a time range),
- correctly identify tangents to curves on displacement–time graphs,
- use tangents to curves to find the speed of an object at an instant,
- recognize that if the tangent is a horizontal line, then the speed is zero,
- recognize that the greater the slope of the tangent, the greater the instantaneous speed at that point.

#### Prerequisites

Students should already be familiar with

- the difference between distance and displacement,
- the difference between speed and velocity,
- how to calculate the speed of an object from distance and time values,
- how to calculate the velocity of an object from displacement and time values,
- how to calculate average speeds and velocities from distance–time graphs and displacement–time graphs,
- how to convert between common speed units.

#### Exclusions

Students will not cover

- relating curved-line displacement–time graphs to their corresponding velocity–time graphs,
- calculating what the tangent must be based on the function of the curve/differentiation.