Lesson Plan Industry Sector
Transportation

## **The 4 strokes of an engine (updated) by Curt Erales

### Lesson Plan Overview / Details

This lesson is designed for entry level students to understand the four strokes of an engine and how a 4 stroke engine functions.

One class
55 Minutes

### Objectives and Goals

Students will understand the operating principles of internal and external combustion engines.

### Activities in this Lesson

• Smoking tail pipe - Hooks / Set

After the students are seated, ask the question, “Has anyone ever wondered why a car smokes?"

The lecture will be on intake, compression, power and exhaust, which are the four strokes of an engine and what happens in each stroke. The diagram shows all four strokes. The importance of each step will be tied in.

• 4 stroke cycle - Lecture

This lesson is designed for entry level students to understand the four strokes of an engine and how a 4 stroke engine functions.

The engines of cars actually have multiple cylinders. The movement of the piston from the top of its travel to the bottom of its travel is called a stroke. Each cycle required to the air-fuel mixture has 4 strokes.

During the intake stroke, the piston is pulled down by the turning of the crankshaft, creating a vacuum above it.

The piston moves back up in the cylinder on the compression stroke, compressiing the air-fuel mixture. As the piston approaches the top of its travel, a spark ignites the mixture.

During the power stroke the burning fuel expands rapidly, forcing the piston to move back down in the cylinder. The exhaust valve opens as the piston approaches the bottom of its travel. This is so that burning gases can escape before the piston begins to move upwards in the cylinder again.

During the exhaust stroke the piston moves back up forcing any remainding exhaust form the cylinder through the open exhaust valve. As the crankshaft rotates, the piston goes back down in the cylinder as the 4 stroke cycle repeats itself.

• Students working - Projects

The student is allowed to explain step-by-step the four strokes of an engine.

Students will be evaluated on their performance test in which each student is given 2 minutes to explain the four strokes of an engine.

Individual students will be directed through a step-by-step process. Actual practice will come after the demonstration.

• Teacher uses this picture to demonstrate all the functions of the 4 stroke engine,including the functions of the intake and exhaust valves, pistion and spark plugs.. [ View Image ] [ Download Original ]
• Students will use the handout as a guide to explain in detail the concept of the four stroke engine. [ View Image ] [ Download Original ]

### Assessment

Assessment Types:
Projects, Demonstrations, Observations,

Re-emphasize the importance of a step-by-step process. Students are put in groups of 4 to allow for peer teaching. Students in groups are asked to explain to each other how the 4 stroke engine works and to tell the difference with each stroke. After this is done I inform students that the next lesson will be on the cooling system.