# Paint and fill the Cylinder

From Karnataka Open Educational Resources

Exploratory activity with paint to understand volume and surface area is approached.

### Objectives

Understand surface area of a cylinder

Understand volume of a cylinder

### Estimated Time

30 minutes

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

- Students are asked to cut paper into rectangular shape of any length (l) and breadth(b).
- Students are asked to cut paper into two congruent circles of circumference=length of rectangle(l)
- Students are asked to make a cylinder using rectangle and two congruent circles.
- Students are asked to use Red paint for painting single side of rectangle and circles and green for filling cylinder

prerequisite knowledge

- What is cylinder?
- Area of cylinder
- volume of cylinder

### Materials/ Resources needed

- instrument box
- Hard paper
- gum tape
- paints-green and red
- brush

### Process (How to do the activity)

- Students are grouped (each group has 4 students). They are asked to calculate the area of rectangle painted and area of circles painted.
- Students are asked to find out the quantity of green paint used to fill the cylinder.

- Developmental Questions:

- which shape the rectangular paper takes when rolled?
- What is the circumference of the circle?
- What is the relation between length of rectangle and circumference of the circle?
- what is the area of rectangle?
- what is the area of circle?

- Evaluation

- How much curved surface area of the cylinder is painted?
- How much area of the cylinder is painted?
- How much green paint is required to fill the cylinder?

- Question Corner

- List out the cylindrical objects that you come across in your surroundings and calculate their areas
- compare them with their respective rectangle and circle.