Reactivate prior knowledge of factors and prime numbers.
Every number greater than 1 is either prime or composite
"Composite" means made up of various parts.
Composite numbers made up of prime factors
Demo: 2-15 (30 seconds)
Factor tree for 18. Grade 7+ expectation of exponential notation is shown as a bonus item, a way to make it REALLY tidy.
2nd example: 48, includes exponents.