Using the prime factor circles on Polypad can help students make meaning of finding common factors of numbers. Below are two videos showing some ways in which students could find common factors (including the greatest common factor) of 336 and 1260.
Target Grades5 – 7
Common Core Standards6.NS.B.4Find 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.