# Surface area of a cylinder

The shape can be thought of as a circular prism. Cylinder could be closed or open. Surface areas for a cylinder is investigated.

### Objectives

To find surface area of a cylinder

40 minutes.

### Prerequisites/Instructions, prior preparations, if any

1. The cylinder is a 3 dimensional solid having curved lateral surface with two circular surfaces on either sides.
2. Basics of circle and rectangle.
3. Formula to find the area of a circle and a rectangle.

### Materials/ Resources needed

Digital: Laptop, internet link, projector and a pointer.

Geogebra file:

### Process (How to do the activity)

1. The teacher can initially discuss about cylinder as a shape and explain its parts.
2. She can then talk about what area means.
3. Discuss regarding surfaces to be covered in deriving the formula for surface area of the cylinder.
4. Project the video and discuss.

Developmental Questions:

1. Can youn identify the shapes of the open cylinder?
2. What is the radius of the circle ?
3. What is the formula to find the circumference of the circle.
4. Into what shape does the curved surface of the cylinder opens ?
5. What are the measures of height and breadth of the rectangle?
6. What is the formula to find the area of the rectangle ?
• Evaluation:
1. Can you explain the conversion of circumference of the circle into the length of the rectangle ?
• Question Corner:
1. What is the difference between lateral and total surface area ?
2. What are the formulae for lateral surface area and total surface area ?
3. Name a few situations wherin one may have to find only the lateral surface area of the cylindrical object ?