Identifying Prime Numbers and Multiples

This lesson explores the properties of prime and composite numbers up to 100 using multiples. Students follow a problem set to identify prime numbers by crossing off multiples of each number starting from 2. The process continues with numbers 3, 5, 7, 11, 13, 17, and 19. The lesson concludes with a list of prime numbers and an explanation of why they are not crossed off, emphasizing that prime numbers have no factors other than one and themselves.

What is the main focus of this lesson?

• Exploring properties of even numbers

• Exploring properties of prime and composite numbers

• Learning about fractions

• Understanding basic arithmetic operations

What is the first step in the problem set?

• Cross off all even numbers

• Circle all prime numbers

• List all numbers up to 100

• Shade number one red

What should you do after identifying the first unmarked number?

• Ignore it and move to the next number

• Shade it blue

• Cross off every multiple of that number

• Add it to a list of prime numbers

Which number do you start with when crossing off multiples?

• 3

• 5

• 2

• 7

What is the next unmarked number after 2?

• 5

• 6

• 3

• 4

What is the next step after crossing off multiples of 3?

• List all numbers up to 50

• Circle the number 4

• Shade number 5 red

• Cross off multiples of 5

What is the next unmarked number after 5?

• 6

• 7

• 8

• 9

What is the next step after crossing off multiples of 7?

• Circle the number 8

• Shade number 9 red

• List all numbers up to 70

• Cross off multiples of 11

What is the next unmarked number after 11?

• 15

• 14

• 13

• 12

What is the next step after crossing off multiples of 13?

• Circle the number 14

• List all numbers up to 130

• Cross off multiples of 17

• Shade number 15 red