The focus of this unit is the extension of operations to algebraic reasoning by gaining familiarity with common factors and multiples, generating and analyzing patterns and sequences, and exploring the importance of primes as they relate to composites. The unit also supports a unification of the strand of number and operation with the strand of geometry. Students learn about the mystery of triangular numbers, build a sequence, and examine patterns in it. They transform quantities into geometric shapes, explore sequences of squares and cubes of primes, and eventually are introduced to the Fibonacci sequence and the related spiral, where the mystery and wonders of number are connected to the beauty and regularity of nature around them. The unit also develops the relationship of multiplication and division by connecting factors to divisors and supports the automaticity of the basic facts.