In order to make the best use of this set, students should first do the activity of Discovering the Rules of Divisibility (available in this store).
The most advanced set of Find Factors cards includes ALL numbers 0-144, including primes. On the back of each card is the set of whole numbers factors AND prime factorization. I find that younger students LOVE learning to make factor trees, circling primes along the way, putting the primes in numerical order, and, best of all, using exponents and a dot for the multiplication symbol!
PRINT 2-SIDED IN COLOR ON CARD STOCK - Instructions for doing so are on page 1 of the download.
"Divisibility - Learning and Games" (free in this store) suggests some ways of using these cards and the Rules of Divisibility to teach prime factorization.
Susan, Morris Tutoring Productions