Lesson Plan - Get It!
- Why is six afraid of seven?
Because seven is a prime number and prime numbers can be intimidating!
Math is full of numbers!
Those numbers are often made up of smaller numbers called factors. Factors are numbers that are multiplied together to create another number. You can use a multiplication chart to help you identify the factors of a number. Some numbers have many factors, while other numbers have exactly two factors. These are called composite and prime numbers.
Prime numbers have exactly two factors. The factors are the number "1" and the number itself. Some examples of prime numbers are:
2: 1 x 2
7: 1 x 7
11: 1 x 11
The number 2 is the only even prime number.
Composite numbers are numbers with more than two factors. Some examples of composite numbers are:
10: 1 x 10, 2 x 5
12: 1 x 12, 2 x 6, 3 x 4
15: 1 x 15, 3 x 5, 5 x 3
Composite numbers can be even or odd.
But wait! The numbers 0 and 1 are neither prime nor composite because they can only be divided by themselves. So, besides 0 and 1, if a number is not prime, it is composite.
If you are able to quickly identify prime numbers, it can help you with division, fractions, and even in your own life! Have you ever had something that you didn't want to share with anyone else? If the number of things you had was a prime number, it cannot be divided between you and anyone else! It is all yours! Now, this is also true of odd numbers in some cases, but if it is you and a friend, you cannot split up a prime number of items greater than two.
Any composite number can be broken down into smaller prime numbers. This is called prime factorization. Prime factorization is a fancy way of saying that you are finding the numbers that multiply together to give you a larger number. Except for one thing, you want to find the special prime numbers!
Before we move on, learn more about Prime & Composite Numbers (requires Flash Player) with a lesson from Scholastic, Inc., StudyJams!. Start with the STEP BY STEP lesson and work with an adult or teacher. Test yourself when you are finished to see if you are ready to move on.
Then, complete the Prime Factorization (requires Flash player) lesson from Scholastic, Inc., StudyJams!, by going through this step-by-step lesson with an adult or teacher. After the video, complete the TRY IT! section and rewatch the video if you aren't ready to move on!
As an added bonus, learning about divisibility rules will help you with finding factors of numbers. If you have time, complete the Divisibility Rules (requires Flash Player) lesson from Scholastic, Inc., StudyJams! Or, come back and do it at another time! After the video, complete Test Yourself and rewatch the video if you aren't comfortable with the divisibility rules.
Discuss with your parent or teacher:
- How would understanding the divisibility rules help you identify prime and composite numbers?
- Are all odd numbers also prime numbers?
- If you are making something to share with others, why would it be important to know about composite numbers?
Now, let's go face our prime number fears in the Got It? section by playing Slap Happy! and modeling prime numbers with tiles!