In Class 7 Mathematics ICSE, the topic of circumference and area of a circle is introduced. Students learn about the basic concepts related to circles, including the definitions of the radius, diameter, circumference, and area. They also learn how to calculate the circumference and area of a circle using formulas.

The formula for the circumference of a circle is (C = 2 times pi times r), where (r) is the radius of the circle and (pi) is a constant approximately equal to 3.14159.

The formula for the area of a circle is (A = pi times r^2), where (r) is the radius of the circle.

Students also learn about the relationship between the circumference and diameter of a circle, which is given by the formula (C = pi times d), where (d) is the diameter of the circle.

Through various examples and problems, students practice applying these formulas to find the circumference and area of circles of different sizes.