http://www.greenemath.com/
In this lesson, we will introduce the concept of a prime number. A prime number is a whole number larger than 1 that is only divisible by itself and 1. Additionally, we will learn that a composite number is a whole number larger than 2 that is divisible by some whole number other than itself and 1. We will then learn how to factor a whole number into the product of prime factors. This process is known as finding the prime factorization of a number. This can be done using a factor tree or division ladder to visually organize the information.
00:00 Introduction
00:21 Prime Number definition
02:44 Check to see if a number is prime
09:51 Composite Number definition
11:14 0 and 1 are Neither
11:47 Determine if Prime, Composite, or Neither
16:33 What are Prime Factors
17:35 Factoring a Whole Number
18:51 How to Use a Factor Tree
21:12 Factoring Whole Numbers Examples