Eratosthenes invented a system called Sieve of Eratosthenes to find out prime numbers. It is a mathematical tool used to discover all possible prime numbers. It is any pattern or algorithm that functions by crossing off potential numbers that do not fit certain criteria.
To understand the concept of prime and composite numbers better students of class 6 were asked to make grids having squares of dimension 1cm x 1cm using sketch pens on half chart paper. They were then asked to cross out every second number except 2 on the grid, every third number except 3, and so on. Students had to check divisibility by 2,3,5 and 7 only. All the encircled numbers were prime numbers and the crossed numbers were composite numbers.
Through this activity, students found out prime numbers easily, understood the concept of divisibility and the inverse relationship between multiplication and division. They actively participated in this activity and helped each other by sharing views and ideas.