First, students will learn how to find the GCD and LCM of whole numbers using Venn diagrams. This method will usually be faster than listing factors and multiples.
Next, students will learn how to find the GCD and LCM by looking at the minimum and maximum of each exponent, in the prime factorization of each number. This method has an advantage over the others, in that it can be used to find the GCD or LCM of any number of numbers.
Conclude by leading this investigation:
6.NS.B.4: Find the greatest common factor of two whole numbers less than or equal to 100 and the least common multiple of two whole numbers less than or equal to 12. Use the distributive property to express a sum of two whole numbers 1-100 with a common factor as a multiple of a sum of two whole numbers with no common factor. For example, express 36 + 8 as 4 (9 + 2).