Introduction:
In class 7, students learn about different mathematical concepts, including area and perimeter. These concepts are crucial in understanding the measurements of two-dimensional shapes. Let's delve into the details of area and perimeter.

Area:
The area of a shape refers to the amount of space it occupies. It is measured in square units, such as square centimeters (cm²), square meters (m²), etc. The formula to calculate the area depends on the shape:

1. Square: The area of a square is given by the formula A = side², where A represents the area and side represents the length of one side of the square.

2. Rectangle: To find the area of a rectangle, multiply its length by its breadth. The formula is A = length × breadth.

3. Triangle: The area of a triangle is calculated using the formula A = ½ × base × height. Here, the base and height are perpendicular to each other.

4. Circle: The area of a circle can be found using the formula A = πr², where A represents the area, π is a mathematical constant approximately equal to 3.14159, and r denotes the radius of the circle.

Perimeter:
Perimeter refers to the total length of the boundary of a shape. It is measured in linear units, such as centimeters (cm), meters (m), etc. The formulas to calculate the perimeter of different shapes are as follows:

1. Square: The perimeter of a square is given by the formula P = 4 × side, where P represents the perimeter and side represents the length of one side of the square.

2. Rectangle: To find the perimeter of a rectangle, add the lengths of all its sides. The formula is P = 2 × (length + breadth).

3. Triangle: The perimeter of a triangle is calculated by adding the lengths of all its three sides.

4. Circle: The perimeter of a circle is also known as its circumference. It can be found using the formula P = 2πr, where P represents the perimeter and r denotes the radius of the circle.

Conclusion:
Understanding the concepts of area and perimeter is essential in solving mathematical problems related to measurements. By applying the appropriate formulas, one can easily calculate the area and perimeter of various shapes. Practice and familiarity with these concepts will enable students to solve more complex problems in the future.